Egyptian-mediated talks between Israel and Hamas ended Monday without an agreement on a prisoner exchange.

After Israeli envoys returned from Cairo, Prime Minister Ehud Olmert accused Hamas of hardening its positions and going back on understandings formulated during the past year.

A Hamas spokesman said there was progress in the talks, but that differences remain.

The envoys were discussing a prisoner swap.  Israel seeks the return of Gilad Shalit, an Israeli soldier captured in 2006 by Palestinian militants in the Gaza Strip.  Hamas wants freedom for hundreds of Palestinian prisoners in Israeli prisons.

Mr. Olmert scheduled a Tuesday cabinet meeting to discuss the prisoner issue.

He has insisted that without Shalit's release, there will be no agreement on a long-term truce in and around Gaza that would allow Israel to open the enclave's borders to reconstruction aid after Israel's recent offensive.

Also Monday, a group of international war crimes experts called on the United Nations to look into allegations that both Israeli forces and Palestinian militants in the Gaza Strip violated humanitarian law during their recent war.

In an open letter, the experts asked U.N. Secretary-General Ban Ki-moon to look into the targeting of civilians by both sides, along with other issues.

Israeli officials say their military made every effort not to target innocent civilians.

In political news, Israel's Prime Minister-designate Benjamin Netanyahu signed a coalition agreement Monday with the ultra-right Yisrael Beitenu party.

Israeli media report that Yisrael Beitenu secured leadership of the foreign ministry along with the ministries of internal security, infrastructure, tourism and integration of new immigrants.

Some information for this report was provided by AFP, AP and Reuters.