BELFAST -- The shipment was purported to contain Lebanese bathroom tiles. But under a thin layer of tiles, was a different and deadly cargo: 200 Czechoslovak-made Kalashnikov rifles, 90 Browning pistols, more than 30,000 rounds of ammunition, 450 fragmentation grenades and 10 RPG-7 rocket launchers with dozens of rockets. Such shipments to Northern Ireland usually are destined for the professional gunmen of the outlawed Irish Republican Army. But, as investigators have said, this load in January 1988 was earmarked instead for three of the Protestant paramilitary organizations that are the IRA's sworn foes. And the ultimate supplier was not Christian militiamen in Beirut looking to peddle some of their surplus arms, as a cover story had it, but Armscor, South Africa's state-run weapons manufacturer. For years, the IRA has been supplied with weapons from sources in the United States, Europe and Libya. Now, British and Irish security sources say, underground Protestant groups also have entered the international arms bazaar. Thus, despite a dramatic increase in the amount of arms seized by British and Irish police, both Catholic and Protestant paramilitary groups are better armed than ever before. "It's safe to say they've got sufficient automatic weapons to keep them going until well into the 1990s," said a senior security official. Some of the weapons sold to the loyalist Protestant groups have already appeared on the streets of Belfast. Michael Stone, the loyalist gunman who single-handedly attacked an IRA funeral in West Belfast in March 1988, killed three mourners and wounded dozens more with a South African-supplied pistol and several grenades. Loyalist gunmen burst into a Belfast bar later in the year and sprayed the room with automatic rifle fire, killing three Catholics with Kalashnikovs from the shipment. And there have been two RPG-7 attacks in recent months on offices of Sinn Fein, the legal political party that supports the IRA. No outsiders knew where these weapons had come from until French police disguised as hotel porters and waiters swooped down on five men in a room at the Paris Hilton four months ago. There they found a South African diplomat, an American arms merchant, three representatives of Ulster Resistance, which is one of the underground Protestant groups, and a demonstration model of a British-made missile system. The diplomat and two colleagues were expelled, the American was released on bail and the loyalists remain in jail facing charges of arms smuggling and conspiracy to engage in terrorism. But from the trickle of information that has emerged, British and Irish security officials have pieced together much of the story of the South African connection. This account is based on information from those sources, who insisted on anonymity, and from sources inside the paramilitary organizations. The Protestants' search for foreign weapons was initiated by Ulster Resistance, set up in 1986 in the aftermath of an Anglo-Irish accord that gave the Irish government in Dublin a consultative voice in the North on behalf of the province's Catholic minority. Ulster Protestants opposed the accord. The key figure in the weapons quest was said to be Noel Little, a clerical worker at a local school board in Northern Ireland and a political supporter of the Rev. Ian Paisley, the right-wing loyalist leader. According to these sources, Little traveled to Europe several times in 1987 and 1988 and eventually made contact with Armscor through American arms dealer Douglas Bernhardt, who served as middle man for the deal. Although Paisley was an early and enthusiastic sponsor of Ulster Resistance, he has since claimed to have cut all ties with it and denies any knowledge of its arms dealings. Ulster Resistance, the sources say, joined forces with the Ulster Defense Association and Ulster Volunteer Force to obtain arms. They had cash -- about $500,000 taken from a bank robbery in the town of Portadown in July 1987. They reportedly used about half that sum to pay Armscor for last year's shipment. To cover its own tracks, Armscor reportedly arranged through agents for the arms to be sent from Christian militia groups in Lebanon. Armscor's agents, by this account, were after something far more elusive and valuable than money: design plans and working parts for the sophisticated ground-to-air missiles, code-named Javelin and Starstreak, being manufactured or under development at Short Brothers, the Belfast arms maker. They allegedly offered Little and his group several million dollars if he could deliver. Ulster Resistance apparently tried to oblige. Last November, a simulator aiming device for a Javelin missile was stolen from Short Brothers. In April, someone took a cutaway model of an older Blowpipe missile from a Northern Ireland base of the Territorial Army, Britain's equivalent of the National Guard. That cutaway model is said to have made its way to the Paris Hilton along with Little and two accomplices, James King and Samuel Quinn, a Territorial Army sergeant major who instructs troops in the use of Blowpipe and Javelin missiles. The Blowpipe is considered an outmoded missile system and a cutaway model with no working parts is unlikely to have impressed Armscor. Some sources suggest Little was seeking either to trick the South Africans or to demonstrate he could deliver the real goods later on. Others say he was set up by British or French intelligence, and still others that officials may be withholding information about just what Little had brought for exchange. In any case, it turned out that French police had kept Storm and Bernhardt under surveillance for months. When the net dropped, Storm claimed diplomatic immunity and was released and expelled. Soon after, Britain also expelled three South African diplomats from London. South Africa, embarrassed by allegations that it had supplied weapons to loyalist "terrorists," expressed its public regrets. Then-president Pieter W. Botha reportedly sent a personal letter of apology to British Prime Minister Margaret Thatcher. Defense Minister Magnus Malan denied that his government was "directly involved in the sale or delivery of South African weapons" but added that "Armscor, above all, is interested in satisfying South Africa's requirements," leaving open the possibility of foreign sales. The government of Israel denied allegations by a Northern Ireland member of Parliament that it had cooperated with Armscor in procuring the weapons for the loyalists. Guns are a thriving black-market business in Northern Ireland. Last year, security forces boasted a record number of arms seizures, including 59 machine guns, 215 rifles, 153 handguns, 15 rocket launchers, 105,049 rounds of ammunition and 20,858 pounds of explosives. Still, sources estimate that these numbers amount to no more than 5 percent of the total weapons and explosives available to the two sides. The IRA's sources of weapons are well known. When French customs agents seized the boat called Eksund in October 1987, they found 150 tons of sophisticated arms, including more than 20 SAM-7 surface-to-air missiles, two cases of RPG-7 rocket launchers, 1,000 Kalashnikovs and two tons of Semtex, the odorless, state-of-the-art plastic explosive from Czechoslovakia, all of it supplied by Libya. Security sources say an equal quantity of weaponry made its way to the IRA in four prior shipments. IRA operatives shot down a Lynx military helicopter last year, using a heavy machine gun that likely came from one of those shipments. Despite denials by foreign governments of involvement in weapons sales, and despite major seizures of weapons, the violence and flow of guns in Northern Ireland continues. Last year, 39 British soldiers and policemen were killed -- the highest number since the early 1980s. And the IRA alone is estimated to have stashed from one to four tons of Semtex, enough to blow up the entire city of Belfast. Late last month, IRA operatives exploded a truck filled with 1,000 pounds of homemade explosives alongside Belfast's well-guarded courthouse. No one was killed, but the explosion demonstrated yet again the IRA's ability to strike and the large variety of weapons it has to choose from.