US Secretary of State Condoleezza Rice warned Iran on Friday that Washington had beefed up its security presence in the Gulf and would not hesitate to defend Israel and other allies in the region.

"We will defend American interests and the interests of our allies," Rice said, answering a question on an Iranian threat to "set fire" to Israel.

"We take very strongly our obligation to defend our allies and we intend to do that," she said at a news conference in Tbilisi.

"In the Gulf area, the United States has enhanced its security capacity, its security presence and we are working closely with all our allies... to make (sure) they are capable of defending themselves," she said.

The comments by the United States' top diplomat came after Iran again ratcheted up its rhetoric against the West and test-fired a series of missiles on Wednesday and Thursday. One of the missiles tested has the range to reach Israel and US bases in the Gulf.

Rice did not specify the steps the United States had taken to boost its security presence in the Gulf, but said its plans focused on Washington's "determination to prevent Iran from threatening our interests or the interests of our friends and allies.

"I don't think the Iranians are too confused either about the capabilities and power of the United States," Rice said on a brief visit to the former Soviet republic of Georgia.

An escalation in tensions has fuelled international concern that the stand-off over the contested Iranian nuclear drive might lead to armed conflict.

US Defence Secretary Robert Gates played down such fears on Wednesday, saying war between the United States and Iran was not close and that everyone realised "what the consequences of any kind of a conflict would be."

The West and particularly Israel fear Iran may be trying to develop nuclear weapons under cover of its stated aim of developing a civilian nuclear energy programme. Iran denies that allegation.

On Tuesday an aide to Iranian supreme leader Ayatollah Ali Khamenei, Ali Shirazi, said Iran would "set on fire" Israel and the US navy in the Gulf as its first response to any American attack over its nuclear programme.

Iran's President Mahmoud Ahmadinejad also called for US military bases across the world to be "eradicated."

Then on Wednesday Iran drew an international outcry by test-firing from the Iranian desert a missile capable of reaching Israel.

Tests continued on Thursday with the firing of missiles by Iranian naval forces, Iranian state television said.

Rice on Thursday said Iran had been offered incentives in negotiations aimed at ending the stand-off over Iran's nuclear intentions and called for Tehran to respond positively.

She said it was time for Iran to "get on the right side of the international community. It ought to be talking about that, not about threats against America or threats against America's allies because frankly it's not going to do them any good," Rice said.

In Moscow Russian Deputy Foreign Minister Sergei Kislyak maintained Moscow's generally soft-spoken approach, urging Tehran to take up technological and economic incentives that the West had offered in return for suspending uranium enrichment.

"If our Iranian colleagues look seriously at the opportunities these proposals represent, there is a huge field for serious, constructive cooperation," Kislyak was quoted by RIA Novosti news agency as saying.

Rice meanwhile also alluded to US plans for a missile defence system in eastern Europe intended in part to reduce the Iranian threat.

She had previously signed an agreement in Prague by which the Czech Republic would host part of the proposed missile shield.

Rice said the system would "make it more difficult for Iran to threaten, be bellicose and say terrible things."

Ex-Soviet Georgia is a close ally of the United States and is located north of Iran in the Caucasus mountains.

Rice was here to affirm US support for the pro-Western course of Georgian President Mikheil Saakashvili.