Arab leaders continued their talks behind closed doors here today, seeking to reach agreement on a common set of proposals to serve as a basis of negotiation with the United States and Israel for a Middle East peace settlement.

The 14 Arab chiefs of state, Palestine Liberation Organization leader Yasser Arafat and five other delegations attending the summit continued yesterday's meeting until 3:30 a.m. today and then reconvened later in the day to discuss the various Arab plans as well as President Reagan's peace initiative, conference sources said. No agreement has been reported.

But proposals submitted by Saudi Arabia's King Fahd and Tunisian President Habib Bourguiba reportedly were being studied by a special committee set up to draft a common Arab approach to negotiations.

The six-member committee was understood to include the leaders of Saudi Arabia, Jordan, Syria and Morocco, as well as Arafat and the Tunisian secretary general of the Arab League, Chedli Klibi. They are regarded as the key figures in inter-Arab negotiations on a joint peace plan.

According to one report, Arab leaders were planning to send a delegation to Washington to discuss President Reagan's proposals and the results of the summit with administration officials. But there was no official confirmation of this report and it appeared to assume some agreements could be reached on the terms of a joint Arab peace plan.

PLO sources told reporters today that the group's executive committee studied the Reagan proposals during a meeting in Tunis over the weekend and found both positive and negative aspects to them. The PLO has not taken a formal public position on the proposals, however, apparently in order to leave room for further negotiations here.

They also said Arafat had been given full power to negotiate on the PLO's behalf here, even though two radical Palestinian leaders, George Habash and Nayef Hawatmeh, were not involved in the Tunis meeting and have denounced the Reagan peace initiative.

A senior aide to Arafat was quoted Tuesday as saying the PLO has rejected President Reagan's Middle East peace plan, Reuter reported. The independent Beirut newspaper An Nahar said Salah Khalaf made the statement Monday when he visited northern Lebanon, still a stronghold of Syrian and Palestinian forces.

"We reject it as a whole and in detail, though we have said it contains some good points," Khalaf, who also is known as Abu Iyad, was quoted as saying.

Moroccan King Hassan, who is acting as summit chairman, has gone to great lengths to keep the counsels of the 15 Arab leaders gathered here secret, and few details of their deliberations have filtered out.

It is not even known for certain whether all the leaders are meeting here or whether some have gone off to the king's summer palace in Ifrane, 35 miles south of here.

The king has limited the number of those involved in the discussions to the 20 chiefs of state and delegations attending the summit and two advisers for each, thus further restricting news leaks.

The more than 650 Arab, Asian and Western correspondents and technicians here are being kept far away from the Arab delegations, apparently to prevent any news leaks.

The summit is scheduled to end Wednesday night, but observers said it might continue at least until the early hours of Thursday.