President Saika Stevens of Sierra Leone, chairman of the Organization of African Unity, today called on Libya at a meeting of 10 African heads of state to withdraw its troops from Chad.

Adding his voice to a growing volume of African and international concern, Stevens said the Libyan military presence in the war-ravaged central African nation was preventing a solution to the instability there. It has, he added, "exacerbated the problem and made reconciliation [between Chad's 11 guerrilla factions] seemingly intractable."

The extraordinary conference, called to untangle the web of political interests threatening to end Chad's first week of peace in nine months, reflected worry on the part of France and many African leaders about Libya's role and the future intentions of that country's radical leader, Muammar Qaddafi. It was the fifth meeting on Chad's sponsored by Nigeria.

A shaky peace reportedly exists in the Chadian capital, Ndjamena, after fierce fighting in the most recent phase of the war that began in March -- the culmination to date of 15 years of civil war in 20 years of independence.

Chad's interim president, Goukouni Queddei, with the reported help of 4,000 Libyan soldiers, beat one of the country's numerous guerrilla factions for control of the capital. Hissene Habre and his guerrilla forces were reportedly driven from Ndjamena under a barrage of Libyan tank and jet bombardment a week ago.

In his opening speech, Stevens pointedly said that resolution of Chad's civil strife could not be found until "all foreign forces in Chad" were removed.

Later in the meeting Togolese President Gnassingbe Eyadema, without naming Libya, also criticized the Tripoli government.

"The real victors [of the civil war] are the gun-runners and those who aided you physically, even if they did not fight in your place," he said.

Nigeria, one of Chad's neighbors and black Africa's most powerful state, has also publicly condemned the Libyan military presence in Chad. On Sunday the Nigerian minister of state for foreign affairs, Patrick Bolokor, flew to Tripoli to deliver an undisclosed message to Qaddafi.

The meeting here is being held here under the auspices of the OAU's good offices committee, which was created specifically to deal with the Chadian war. The west and central African heads of state are considering an "African solution" to Chad's problems.

In a surprise development today, Chadian President Queddei came to Lagos after announcing in Ndjamena yesterday that the conference was "nonsense" since he ahd won the war and Chad was at peace. He was expected to attend tonight's session.

Late this afternoon, the defeated Habre showed up unannounced at the closed-door session at the Nigerian Institute of International Affairs, but he was rebuffed in his effort to address the conference and left the building. One high-level Nigerian source said that Habre had "blown whatever leverage he had had" with the conference leaders when he refused to sign a cease-fire agreement that Queddei had signed earlier. Habre waited past the Nov. 28 deadline to agree to sign after it was clear that Libyan support of Queddei would lead to his own defeat.

"If he had only signed in time," said the Nigerian source, "then they could really deal with Libya, but as it is now they are more angry with Habre for not using his head."

Libyan Foreign Minister Abdul Salam Treiki arrived from Tripoli at the institute at midday and was admitted to the conference. Treiki refused to discuss conference matters when approached by reporters during a break in the meeting.

French and U.S. intelligence sources have put the number of Libyan troops inside Chad at about 4,000. Chad is a former French colony, and the French government has been particularly perturbed by the large Libyan presence there. g

Both Queddei and Qaddafi have denied that there are large numbers of Libyan troops in Chad. They said Libya had sent some military aid and advisers to Queddei's forces.

All five countries that border Chad, excluding Libya, are known to be concerned about Qaddafi's using Chad as as base to export his brand of Islamic revolutionary fundamentalism to their sizable Moslem populations. The five are Nigeria, Niger, Cameroon, the Central African Republic and Sudan. Sudan was the only East African country represented at today's conference. A government minister was sent.

Recently, three black African countries -- Senegal, the Gamia and Ghana -- broke diplomatic relations with Libya amid reports of Libyan attempts to destabilize their governments.

Qaddafi has been promoting a brand of Islamic revolutionary zeal similar to Iran's in an effort to spread a pan-Islamic, Libyan-led ideology across the northern Sahara.

Queddei's victory with Libyan support has made both France, which pulled out 1,200 peacekeeping troops from Chad last spring, and African countries fearful that Chad will be Qaddafi's stepping stone to his pan-Islamic dream, leading to further instability in central Africa.

One irony of the present situation is that Queddeihs forces fought, severely mauled and defeated a Libyan "invasion column" in northern Chad in the summer of 1979. Egypt and Sudan have reportedly also been involved in Chad on whatever side was anti-Libyan at any one time, as Habre was recently. France also supposedly backed Habre.