The US ambassador at large for war crimes, Clint Williamson, arrived in Cambodia Wednesday for a three-day study of the Khmer Rouge tribunal.

Williamson's visit comes as the US is considering funding for the cash-strapped tribunal, officially known as the Extraordinary Chambers in the Courts of Cambodia, or ECCC.

"While the US wants to be in a position to be able to support the ECCC politically and financially, the State Department is still reviewing all the facts about the tribunal and its operations, including whether or not it is capable of meeting international standards of justice," the US Embassy in Phnom Penh said Wednesday in a statement.

Williamson will meet with tribunal, government and rights officials, including Deputy Prime Minister Sok An, the embassy said.

The US was instrumental in establishing the framework for the hybrid tribunal, which pairs UN-appointed international and national jurists across several offices and court chambers.

Tribunal spokesman Reach Sambath said Wednesday the courts welcomed the visit.

"We have iterated from the beginning that the US is a country involved in this tribunal, and a country that pushed for the formation of the ECCC," Reach Sambath said.

The tribunal, which in recent months has arrested five top Khmer Rouge leaders, opened its doors February 2006, after years of wrangling. Observers now say it will overreach its time limit, and that necessary funds will be needed to keep it running.

But the process has been tarnished by accusations of corruption, kickbacks and a lack of transparency, and US officials have said in the past these need to be overcome before the US will help fund it.

"The US takes seriously allegations of mismanagement or impropriety in the ECCC's Office of Administration," the embassy said Wednesday. "There have been multiple assessments this year of the ECCC's administration, and these are important tools for identifying and correcting weaknesses in the ECCC's operations. The US looks forward to receiving updates on the steps taken by the ECCC's administration to address the concerns identified in these audits."