Two tough new security bills cleared their last legislative hurdle tonight, fueling predictions that the South African government may suspend its nationwide state of emergency once the measures take effect next week.

The controversial legislation will enable the state to assume sweeping new emergency powers without a formal declaration, and to hold political detainees for up to six months without charge and without having access to families or lawyers.

Meanwhile, the government announced six more deaths in the civil unrest sweeping the country, bringing to 54 the number of people killed since the state of emergency was imposed last Thursday. Among those killed this week was a 9-year-old boy shot by a soldier.

This article was written under the already severe press restrictions imposed as part of the emergency declaration and today officials for the government's Bureau for Information, the only authorized source of news about the emergency, tightened their clamps further by setting new restrictions on their daily briefing.

Officials said they would only take written questions submitted by reporters at least four hours before the daily sessions and would not allow journalists to raise other subjects. They also warned television journalists that they were legally responsible for seeing that interviews videotaped in South Africa and transmitted abroad do not violate the broad emergency restrictions on news and comment.

South Africa's largest daily black newspaper, the Sowetan, said today that police had called "subversive" the blank spaces that had been left in the publication to protest the new emergency press restrictions, United Press International reported. An opposition weekly newspaper, the Weekly Mail, published a self-censored edition containing the blacked-out names of more than 1,000 persons allegedly being detained.

Although the outcome of the new security bills had never been in doubt because the government has a parliamentary majority, they had been stalled for two weeks following their introduction because of opposition from the mixed-race and Indian legislators in South Africa's racially segregated tricameral parliament.

The bills were approved tonight by the President's Council, a statutory body controlled by the ruling National Party. Under South Africa's constitution, the council has the power to override any attempt at a veto by the nonwhite houses.

Officials said last week that they were imposing the emergency to cope with antigovernment demonstrations and gatherings planned for June 16, the 10th anniversary of the Soweto uprising. They indicated that the crackdown, in which an estimated 3,000 antiapartheid activists have been detained, would not have been necessary had the two security bills been passed in time.

To become law, the measures now must be signed by President Pieter W. Botha and published in the government gazette. That could happen as soon as Monday, according to David Dalling, opposition justice spokesman in the white legislative House of Assembly.

While security officials will not comment publicly, Dalling said conversations with members of the government led him to believe that after the bills are published, "the state of emergency will be lifted almost immediately, perhaps as early as Monday or Tuesday."

The President's Council, which is made up of representatives of the various parliamentary parties, passed the two bills by votes of 35 to 22 and 35 to 21 along strict party lines. The ruling white party has a built-in majority in the council. Members of the ruling National Party and the white rightist splinter group, the Conservative Party, voted in favor of the bills. The white Progressive Federal and New Republic parties, and the parties in the mixed race and Indian houses voted against them.

The two racial groups, that serve separately in a mixed-race House of Delegates and Indian House of Representatives, had voted last week to delay consideration of the bills for six months, the strongest form of rejection available under this parliamentary system.

Passage today came after a heated 9 1/2-hour debate in which critics accused the government of ignoring the mixed-race and Indian houses to push through the new laws.

R. V. Carlisle, a member of the white opposition Progressive Federal Party, said the new laws were an admission of failure by the government. "We should be stripping them of their powers, not giving them new ones," he said. The abolition of the apartheid system was inevitable, he said, and "to reach for our rifles now will only delay the process. Not to deal with the Americans now might only mean that we will have to deal with the Russians later."

Nic Treurnicht, a Nationalist spokesman, conceded that the legislation was "draconian" and that the government was introducing increasingly drastic laws. But, he said, they were "essential" because South Africa was facing an "onslaught" planned by sophisticated, radical experts and that even harsher security measures might be needed in the future.

"We make this recommendation in the interest of all responsible and order-loving citizens of South Africa," he said.

Under the present state of emergency, detainees can be held for 14 days without charge, after which the minister of law and order must sign a written order to prolong their detention. The new law would extend that period to six months in places the government designates as "unrest areas." Those areas could also be subject to other restrictions and placed off-limits to the press.