A jubilant Cambodian Prime Minister Hun Sen told reporters Monday that he had received a firm undertaking from visiting US Deputy Secretary of State John Negraponte that the US had agreed to fund a trial of former Khmer Rouge leaders.

The announcement ended the first full day of high-level meetings between Negraponte and Cambodian government officials.

"This official visit has strengthened bilateral relations ... I have been informed by the US government that it has agreed to provide assistance to the trial of former Khmer Rouge leaders, but the amount it has pledged will be revealed tomorrow," Hun Sen said.

"This agreement to fund is like the pregnancy of an elephant," Hun Sen joked, referring to the two-year gestation period of the pachyderm. "The elephant is pregnant so long, when it finally gives birth, you hope it will be a very good baby elephant."

Ongoing corruption allegations surrounding the joint UN-Cambodian Extraordinary Chambers in the Courts of Cambodia, currently holding five former leaders on human rights abuses and war crimes charges, had previously been cited as hurdles to funding by the US.

Negroponte did not speak after the meeting at the Foreign Ministry which also featured the signing over by the US of 24 million dollars in bilateral aid for economic projects in Cambodia, but he is scheduled to give a detailed press conference at the US embassy Tuesday before departing Cambodia.

The Khmer Rouge trial to bring former leaders of the 1975-79 regime to justice announced earlier this year that delays and complications had left it in serious need of funding if it was to complete hearings against an undetermined number of accused.

Up to 2 million Cambodians died during the regime.