UNITED NATIONS - Russia and China have delayed promised helicopters and medical units to a UN peacekeeping force in Sudan, thereby causing other countries to postpone sending troops, a UN official said.

The United Nations expects 10,000 troops in southern Sudan to monitor a peace agreement signed a year ago that ended nearly three decades of civil war between rebels and the Khartoum government. But only about 4,000 have arrived.

Jan Pronk, the special UN envoy to Sudan, told a news conference on Friday that Russian transport helicopters and a Chinese medical unit were considered vital before certain nations would send troops.

Russia’s parliament in December approved sending 200 soldiers and four Mi-8 transport helicopters, along with other equipment to Sudan on President Vladimir Putin’s request.

“We are waiting already a year,” Pronk said. “They are essential. We need the aviation units.”

Pronk acknowledged increasing difficulties getting countries to fulfill their contribution pledges in time and in recruiting additional soldiers.

The operation in southern Sudan is separate from an African Union force in Darfur in the west. But the United Nations is contemplating taking over the Darfur venture and will probably run into the same recruitment difficulties as in the south.

Promised money to help development in the south and resettle refugees also has not been delivered, including from the UN budget itself, Pronk said.

But he said donors had to ensure that Sudan allocated its considerable oil resources to benefit the south, because giving money unconditionally “is a waste.”

“Good economic governance is a must because it was bad governance in the past which fueled the conflict,” he said.

However, Pronk said that without international support the expectations of the people in the south would falter.

“That is a major risk. There is peace, indeed, but where is the peace dividend?” he asked.