London, May 2: U.S. Secretary of State Condoleezza Rice voiced scepticism on Thursday about sweetening incentives for Iran to halt sensitive nuclear work and urged tighter enforcement of U.N. sanctions against Teheran. “Diplomacy has many forms ... and it’s not always a matter of sweeter,” Rice told reporters as she flew to London ....

...for meetings on Friday about Iran’s nuclear programme and aid to the Palestinians.

The five permanent U.N. Security Council members and Germany will meet to discuss their long-stymied effort to persuade Iran to suspend uranium enrichment, a process that can produce fuel for nuclear power plants or for atomic bombs.

The United States and some of its allies suspect Iran of using its civil nuclear programme as a cover to develop atomic bombs. Iran denies this, saying its programme is to generate electricity so it can export more of its oil and gas.

Foreign ministers from the six major powers -- Britain, China, France, Russia, the United States and Germany -- plan to examine an idea championed by Russia of dangling more carrots before Iran.

Tehran has so far spurned a June 2006 offer of incentives from the six and has brushed off three U.N. Security Council resolutions that imposed sanctions for its failure to halt the nuclear work.

The benefits offered to Iran if it suspended uranium enrichment and negotiated with the major powers included civil nuclear cooperation and wider trade in civil aircraft, energy, high technology and agriculture.

While saying she was open to discussing a modest improvement in the incentives package, Rice made clear she saw little chance of this working.

“The Iranians haven’t shown any interest -- I don’t care what’s been put before them -- in doing what they need to do, which is to suspend enrichment and reprocessing,” said Rice.

“Nothing has been able so far to change the fundamental problem ... It’s Iran, that’s the problem.” she said.

“We’ve got to intensify our efforts on the U.N. Security Council resolutions themselves. I believe there is plenty in the .... resolutions that if fully implemented, fully executed, fully used, will increase the pressure on Iran.”

Rice will also attend a meeting in London of the quartet of Middle East peace mediators -- the European Union, Russia, the United Nations and the United States -- and a gathering of Palestinian donors.