The United Nations hopes to cut one billion dollars off its peacekeeping budget this year as it seeks to close or shrink many missions, a top UN official said Wednesday.

With major powers pressing for spending cuts, the East Timor peacekeeping mission is expected to close by the end of 2012 and Haiti, Liberia and possibly Darfur could face reductions, said Herve Ladsous, the head of UN peacekeeping.

He told reporters he hopes to cut the department's budget, which dominates UN spending around the world, from $8 billion last year to about $7 billion in 2012.

"There are a number of missions that have gone through the critical stage and probably we will be able to start looking at downsizing," said the under-secretary general.

There are currently about 120,000 troops from 114 countries serving in 16 UN missions around the world. Numbers in the Haiti mission are already being cut and Ladsous said those in Liberia came down after last year's elections.

A review of the UN mission in Darfur, Sudan started this week and Ladsous said similar studies in other operations would be carried out.

Ladsous also said the UN may ban a whole country contingent from a mission if a soldier from that country is found guilty of sexual abuse.

He is seeking a new crackdown on abuse after new cases were uncovered in Haiti, he said.

"It is a matter of concluding that in a case of a particular peacekeeping operation, one contingent may not be up to the standards that we would expect of a peacekeeping contributing state," Ladsous told reporters.

He said no decision had been made yet and no country would be completely banned from UN missions, as other officials have indicated.

The United Nations ordered a "zero tolerance" clampdown after sex abuse cases involving UN troops and police in Haiti, Democratic Republic of Congo and other nations.

"We are presently developing a policy which will go further, much further," Ladsous said. He said the sex abuse cases "contaminate" the image of UN peacekeeping and that once the accused troops or police have faced criminal actions the UN can send them "packing."

Last year six Uruguayan troops in the Haiti mission, MINUSTAH, were accused of raping a Haitian teenaged boy. Last month investigations were started into what the UN called "grave allegations of sexual and exploitation abuses" involving UN police in Haiti.

UN peacekeepers in Democratic Republic of Congo, Liberia and Ivory Coast have also faced dozens of accusations of sexual abuse in recent years.

The UN peacekeeping department insists numbers have been cut in recent years because of its "zero tolerance" efforts.