Iran's supreme leader threatened Wednesday to pull out of negotiations if European countries press their demand for total suspension of uranium enrichment, as a new round of talks ended without an agreement to avert the possible threat of U.N. sanctions.

Britain, France and Germany are trying to work out a deal that would defuse Western concerns about Iran's nuclear program, which the United States says aims to develop nuclear weapons.

The Europeans are offering Iran incentives -- a trade deal and civilian nuclear technology, including a light-water research reactor -- in return for a halt in enrichment, which can produce fuel for both nuclear energy and atomic weapons.

They have warned that most European states will back the United States' call to refer Iran's nuclear file to the U.N. Security Council for possible economic sanctions if Iran doesn't give up all uranium enrichment activities before a Nov. 25 meeting of the International Atomic Energy Agency, a U.N. body.

In talks Wednesday, Iran's delegates insisted on the right to enrich uranium. And the country's supreme leader, Ayatollah Ali Khamenei, ruled out any long-term suspension of the program. "A long-term suspension of enrichment is a discussion without logic," Khamenei said, according to state-run television in Tehran.

Still, Iranian negotiators held out the possibility of a compromise with the Europeans. Iranian and British officials said another round of talks would be held soon.

"We haven't closed the door for an understanding . . . but will reach compromise if there is a balanced package of agreements. Obligations and confidence-building measures have to be bilateral," Hossein Mousavian, Iran's chief delegate to the IAEA, told his country's state-run radio Wednesday. "There has to be no discrimination against Iran."

Iran insists that its nuclear activities are peaceful and geared solely toward generating electricity. The United States, pointing to Iran's vast oil reserves, contends that it is running a covert nuclear weapons program.

Heightening the U.S. concerns, Iran has resumed testing, assembling and making centrifuges used to enrich uranium.

Ayatollah Ali Khamenei rejected the demand made by Britain, France and Germany.