Palestinian President Mahmoud Abbas and Israeli Defense Minister Ehud Barak met briefly Tuesday on the sidelines of a worldwide socialist party conference near Athens.

The two met privately for a half-hour on the sidelines of a three-day Socialist International conference in this coastal resort, 25 miles south of Athens.

After the meeting, Barak said he expected U.S.-backed peace talks with the Palestinians to continue, according to aides who were there when he spoke.

"The Israeli public is ready for painful concessions," he said. "If there will not be peace in this round it will be responsibility of the Palestinians."

Addressing the conference earlier, Abbas said the talks "still face great obstacles" but the chance for a settlement should not be lost.

"There is still a wide gap between the respective positions that cannot be overcome unless the Israeli government adopts positions and measures that will clearly emphasize its sheer desire to seize an opportunity to achieve peace," Abbas said. "But this chance may not remain open forever."

Abbas urged self-restraint from both sides to preserve the shaky, Egypt-brokered truce in the Gaza strip.

"We hope that (the cease-fire) will be kept despite the fact that there are those who are trying to destroy it," Abbas said.

Barak urged Gaza's Hamas rulers to release an Israeli soldier abducted two years ago.

"Hamas and its leadership has a choice: either to accept the quartet conditions and make itself a legitimate actor, including the release of our abducted soldier Gilad Shalit, or continue the way of violence ... leaving us no choice but to defend our citizens," he said.