Egyptian President Hosni Mubarak, whose remarks at the White House Wednesday seemed to dim U.S. hopes for early progress toward Mideast peace, made a more positive gesture toward President Reagan yesterday by publicly endorsing the Camp David peace process for the first time since he arrived here.

Following a second day of White House meetings between the two leaders, Mubarak bid farewell to his host by declaring: "We are determined to pursue our peace efforts until a comprehensive settlement is reached according to the Camp David accords."

That was in marked contrast to Wednesday's arrival ceremony, where Mubarak raised eyebrows with his failure to mention the 1979 Camp David agreements--the cornerstone of U.S. efforts to resolve the Arab-Israeli dispute--and instead put his emphasis on calling for self-determination and "a national entity" for the Palestinian people.

His remarks then were taken as a deliberate signal that Egypt's priorities do not include an early resolution of its 20-month negotiations with Israel over an autonomy agreement for the 1.3 million Palestinian inhabitants of Israeli-occupied territories.

The United States had been put on notice earlier that Mubarak, who became president following the murder of Anwar Sadat last October, wants to take a go-slow approach to the autonomy talks while he concentrates on other goals such as Egypt's internal problems and a reconciliation with the rest of the Arab world.

Nevertheless, U.S. officials, who have been seeking to put the best face on the frustration of their hopes for a breakthrough on autonomy, appeared to have been taken aback by Mubarak's emphasis on phrases such as "self-determination" and "a national entity." Such terms are regarded in Israel as code words for creation of a Palestinian state in the West Bank and Gaza Strip, and Israel has insisted it will not pursue any autonomy negotiations aimed at such a predetermined outcome.

Yesterday, however, Mubarak softened his tone sufficiently to join Reagan in pledging Egypt's continued cooperation with the U.S.-sponsored peace process. Despite the warm rhetoric exchanged by the two presidents, it was clear, though, that Washington now concedes there is little liklihood of any dramatic progress in the near future.

Even Reagan seemed to admit that when he said they had agreed to continue pursuing "a declaration of principles, which is the best means of making tangible progress toward a solution of the Palestinian problem." That was a tacit acknowledgment that the autonomy talks have made no progress since they were resumed in September after a long delay.

But, while yesterday's exchange was essentially cosmetic, U.S. officials appeared relieved at Mubarak's shift toward rhetoric indicating he wants to preserve Egypt's close ties with the United States and is not publicly distancing himself from the Camp David accords.

Some sources suggested the difference could be explained, in part, by the fact that Mubarak's remarks Wednesday were transmitted by television satellite to Egypt. That was not the case yesterday when he was speaking to what the sources called "an American rather than an Arab audience."

The sources also said Mubarak's initial coolness may have been a bargaining chip aimed at strengthening his hand in bidding for greater U.S. economic and military assistance. The administration plans to ask Congress to grant Egypt $1.3 billion in military aid for the coming fiscal year, and Mubarak, who yesterday called the meetings here "very fruitful," appeared to be pleased at the outcome of the aid discussions.

Last night, Treasury Secretary Donald T. Regan announced that the administration has concluded an agreement with Egypt allowing greater leeway in spending $1 billion in U.S. economic aid this year.

Regan made the announcement on the steps of Blair House after a meeting with Mubarak. One aim, Regan said, is to attract more American investment in Egypt.

Details will be made public later, but the Associated Press said that Regan told reporters there was no plan to boost economic assistance to Egypt, already the largest of any single country on the U.S. aid list.