ROME (CNN) -- With a Friday deadline looming for adjournment, delegates to a U.N. conference called to establish the rules for a permanent international criminal court were trying to craft compromise language to appease the United States and other world powers.

The International Criminal Court would be a permanent body to try cases of genocide, crimes against humanity and other war crimes, replacing "ad hoc" courts that have been set up to judge crimes in Rwanda, Bosnia and other places.

But after five weeks of negotiations, there are still wide differences over how much power the court should have -- and even how war crimes should be defined. The deadline for reaching an accord is midnight Friday.

RELATED VIDEO
CNN's Gayle Young reports on the contentious issues
Windows Media	28K	56K

The major sticking point is a provision, being pushed by the United States and France, that would allow countries to refuse to allow their nationals to be tried by the ICC in all but genocide cases for the next 10 years. Both countries have troops widely deployed around the world and fear that their soldiers could face politically motivated prosecutions.

Four of the five permanent U.N. Security Council members -- the United States, France, China and Russia -- support the opt-out proposal presented to the conference by Japan.

But more than 60 other countries from Europe, Asia and the Third World reject it, insisting that it would render the court useless.

Another wrinkle has been India's demand that the use of nuclear weapons be made a war crime -- a measure opposed by the five permanent Security Council members, all of which are nuclear powers.

Many delegates fear that if the blueprint for the court coming out of Rome doesn't have the backing of the United States and other major powers, the ICC will be doomed. There is also a possibility that the conference could be forced to adjourn without an agreement.

But in a spirit of optimism, Italy's government scheduled a signing ceremony for the ICC blueprint on Saturday morning at the site of the ancient Roman Capitol.

Correspondent Gayle Young and Reuters contributed to this report.