Secretary of State James Baker and Soviet Foreign Minister Alexander Bessmertnykh pressed ahead with their efforts to bring all the players together for a Middle East peace conference, sorting through a host of conditions demanded by the nations involved.

Increasing numbers of Kurdish refugees returned to their homes in northern Iraq and the State Department said that U.N. officials had reached a "preliminary agreement" with Iraqi officials to establish a U.N. protective force to guard the Kurds.Baker went to Israel and Bess-mertnykh to Syria Tuesday in an effort to get agreement from the two most hard-line Middle East countries on a peace conference sponsored by the superpowers.

There were kind words and general talk about the desire for peace talks, but the crucial sticking point of a role for the United Nations in the talks remained.

As Baker's fourth - and possibly last without a breakthrough - postwar visit to the area neared an end, President Bush refused to call the effort a "failure," saying there was still room for optimism.

Before traveling to Israel, Baker stopped in Amman, Jordan, where King Hussein said he might invite Palestinians to join the Jordanian delegation to a peace conference.

"If our Palestinian brethren approach us for a joint delegation to address themselves the Palestinian-Israeli dimension of this conflict, it is something well look at very favorably and positively," the king said.

He did not specify whether "Palestinian brethren" meant the Palestine Liberation Organization - a sticking point with Israel.

The secretary of state said that while "all the parties with whom we had discussions have agreed essentially to attend a conference" sponsored by the United States and Soviet Union, important procedural problems remained.