Australia says its current election campaign means it is not in a position to give further funding to Cambodia's Khmer Rouge court.

That is despite an urgent UN warning that "the very survival of the court is now in question".

With help from international donors, the Cambodian government pays local staff at the special court - set up to try those responsible for atrocities committed by the 1970s Khmer Rouge regime.

But about 200 locally employed court staff have stopped work this week because they have not been paid since June.

The UN pays international staff also with support from donors, including Australia which is the second largest donor to the court behind Japan.

Australia has contributed $23 million so far, the last payment of $3.25 million in June this year, when trials which began in 2006 looked like falling over for financial reasons.

Government spokesman Ek Tha says the court is seeking further contributions from international donors.

"We are seeking not only Australia, Canberra, we are seeking other donors, Japan, new and old donors to come up with more funds for the national side of the court because this court cannot work without national side and international side, this court cannot work without one another," he said.

"So of course a plane or a bird cannot fly with one wing."

The court has convicted just one Khmer Rouge leader so far.

Of four defendants in the second trial, one has died and another has been excluded due to senile dementia.

A verdict on the case of the remaining defendants - so-called Khmer Rouge Brother Number 2 Nuon Chea, who was second in charge to late leader Pol Pot, and former head of state Khieu Samphan - is expected in mid 2014, if the court can survive that long.

Court spokesman Neth Pheaktra says there are serious concerns that the outcome of that case will be affected if funding is not forthcoming.

"We are very concerned on the very survival of the court," he said.

The Cambodian government's commitment to the court has long been questioned.

However Ek Tha denies the government is using lack of finance as an excuse to bring the process to a close.

He says the government is trying to get further international support but a meeting with Australian ambassador Alison Burrows yesterday was unsuccessful.

"Australian government in the meeting this morning, Madam Alison Burrows said ... at this time there's no more funding for the national side of the court, so what can we do?" he said.

"We continue to seek more financial contributions from old and new donors."

A spokesman for Foreign Minister Bob Carr says further funds cannot be committed ahead of this weekend's election.

He says it will be up to a newly elected government to give consideration to further funding the court.