The joint mission is set to begin in six weeks
The joint UN-African Union peacekeeping mission to Darfur may fail unless countries can provide helicopters and lorries, a top UN official says.
Foot-dragging by Sudan over the make-up of the force could also threaten the mission, he warns.
The 26,000-strong force is aiming to bring security to the region after more than four years of conflict.
The deployment is scheduled to begin in six weeks, but could be delayed if the necessary equipment is not received.
Jean-Marie Guehenno, head of the UN peacekeeping department, told reporters the force needed six attack helicopters and 18 transport helicopters.
He also expressed concern that the Sudanese government had yet to authorise the make-up of the deployment.
BBC Africa editor David Bamford says it seems Western countries have been slow in providing the equipment because they lack confidence in the control structure of the joint force, which the UN has agreed must be African-led.
Sudan wants the force to consist predominantly of African troops, and is unhappy that peacekeepers from Thailand, Nepal and Norway have been added to the force.
The UN says that the force will still be three-quarters African, and that other troops from African countries are not up to scratch.
"If those issues are not addressed it means that the mission in 2008... will not be able to make the difference that the world wants it to make and that it may become a failure," said Mr Guehenno.
"I think it tells a sad story on the commitment for Darfur, frankly," he continued.
"We believe that now is the time really to face very important decisions, because the clock is ticking."
French ambassador to the UN, Jean Maurice Ripert, criticised the government in Khartoum's perceived lack of action.
Some 200,000 people have been killed in Darfur since 2003
He said: "[The Sudanese authorities] should stop arguing on each and every detail on the ground."
But Khartoum said it was optimistic the military deployment would go ahead by early 2008.
Sudanese ambassador to the UN Abdalmahmood Abdalhaleem Mohamad said: "We have already a large number of African [forces] ready to take their place in Darfur. We are not lacking at all those forces."
The Khartoum government and Arab militias allied to it have been blamed for massacres of Darfur's black African population, charges the government denies.
An African Union (AU) peacekeeping force has been in place since 2004, and it is now made up of some 7,000 troops.
In July 2007, the UN Security Council authorised the establishment of a new 26,000-strong joint UN-AU force.