WASHINGTON (AFP) - The United States said on Tuesday that it expects to participate in Cairo talks between Israelis and Palestinians aimed at securing a lasting ceasefire in Gaza.

"I think it is likely we will be participating in these talks," State Department spokeswoman Jen Psaki told reporters.

"We are determining at what level and in what capacity and when." Israeli and Palestinian delegations headed to Cairo on Tuesday as a 72-hour truce took hold in the Gaza Strip, after 29 days of fighting that has killed 1,875 Palestinians and 67 people in Israel.

When asked if the two sides had sought a US presence at the negotiating table, Ms Psaki said: "I think our effort and our engagement on this process from the beginning has been welcomed by the parties."

US diplomats seemed to be caught by surprise on Monday by Egypt's announcement of a truce proposal, which was eventually hailed by the White House.

Washington, however, underlined the need for Islamist movement Hamas to make good on its promises.

"I think our engagement over the past 10 days has built and led to the point we reached last night," Ms Psaki said, mentioning US Secretary of State John Kerry's efforts on the issue, both in the region and from Washington.

The ceasefire took effect early Tuesday.

Officials on both sides confirmed they had sent small delegations to Cairo for talks aimed at securing a permanent ceasefire after the three-day window closes.