U.S. Vice President Dick Cheney says Washington wants to deal with Iran through diplomacy, but he says "all options are still on the table" to prevent Tehran from getting nuclear weapons.

At a news conference with Australian Prime Minister John Howard in Sydney Saturday, Cheney said the U.S. government has worked with Europeans and the United Nations to persuade Iran to give up its nuclear program, and a peaceful diplomatic solution remains the preference.

Cheney says it would be a serious mistake if Iran became a nuclear power.

On Friday, U.S. Secretary of State Condoleezza Rice said she believes a diplomatic solution could succeed if the international community remains unified in confronting Iran.

The five permanent members of the U.N. Security Council plus Germany will meet Monday in London to discuss Tehran's refusal to stop enriching uranium.

On Thursday, the International Atomic Energy Agency reported that Iran had expanded its uranium enrichment activity, despite a U.N. Security Council order to stop enrichment.

The United States and other major powers allege Iran is trying to build nuclear weapons, a charge Iran denies.

Some information for this report provided by AP, AFP and Reuters.