Sudan is blocking deliveries of rations and other needed supplies for troops serving in the joint UN-African Union peacekeeping mission in Darfur, British Ambassador Matthew Rycroft said Wednesday.

"They are holding up crucial rations and other supplies in Port Sudan destined to UNAMID troops," Rycroft told reporters.

"It has been going on for weeks and weeks and it needs to stop," he said.

Unless Khartoum lifts its blockade, the United Nations will have to take additional measures to deliver the supplies, resulting in millions of dollars in additional costs for the peacekeeping budget.

The total monthly cost will increase from $3 to $13 million to ensure the peacekeepers get the necessary supplies, he said.

Britain is planning to raise the issue at the Security Council on Wednesday.

More than 17,000 troops and police are deployed in Darfur as part of the UNAMID mission set up in 2007.

Darfur has been engulfed by violence since insurgents rose up against Khartoum's rule 12 years ago.

The conflict has left more than 300,000 dead and driven 2.5 million people from their homes.