LONDON: Britain could send further military assets to the Strait of Hormuz to deter any attempt by Iran to block Persian Gulf oil tanker traffic, the country's defense secretary said Tuesday, as Tehran appeared to shrug off a new European Union ban on the purchase of Iranian oil.

Philip Hammond told reporters that two British and French warships and the American aircraft carrier USS Abraham Lincoln had entered the Gulf on Sunday to show Tehran they would not tolerate any interference with global shipping.

Iranian leaders repeated long-standing threats to close off the Strait, which handles a fifth of the world's oil, after the European Union imposed the embargo Monday as part of sanctions to pressure Tehran into resuming talks on the country's controversial nuclear program.

But, other Iranian officials took a slightly different tack Tuesday, arguing that the sanctions simply would not work.

"The world economy is not such that a decision can deprive a country of its existence," the country's intelligence chief Heidar Moslehi was quoted Tuesday by the state IRNA news agency as saying.

During talks in London on Tuesday, Australia said it would also sign up to the embargo — though acknowledged it currently has negligible oil imports from Iran.

The three warships — which included Britain's HMS Argyll frigate — that entered the Gulf on Sunday had sent "a clear signal about the resolve of the international community to defend the right of free passage through international waters," Hammond said.

"We also maintain mine-counter measures vessels in the Gulf, which are an important part of the overall allied presence there, and of course the U.K. has a contingent capability to reinforce that presence should at any time it be considered necessary to do so," he said.

Britain's defense ministry declined to offer specific detail on what assets and personnel are currently in the Persian Gulf, but said it had about 1,500 Navy personnel in the region east of Suez, which includes the Middle East and Indian Ocean.

Four anti-mine vessels are based out of Bahrain, while Britain also has two frigates — including HMS Argyll — three support ships, a survey vessel and one hunter-killer nuclear submarine in the region, the ministry said.

The United States and allies have already warned they would take swift action against any Iranian moves to choke off the 30-mile (50-kilometer) wide Strait of Hormuz.

At the center of the dispute is international concern over Iran's nuclear program, which Tehran insists is aimed at providing civilian power. The U.S. and other nations accuse Iran of attempting to build nuclear weapons, and Tehran is now under several rounds of U.N. sanctions over its failures to be forthcoming about its work.

Hammond said recently that Iran was "working flat out" to produce a nuclear weapon.

Australia's foreign minister Kevin Rudd, in London with Australian defense minister Stephen Smith for talks with British counterparts, said his country would join the EU's oil embargo.

"We in Australia will undertake precisely the same parallel actions in Australia," Rudd said. "The reason is very clear — the message needs to be delivered to the people of Iran, the wider political elites of Iran, as well as the government of Iran that their behavior is globally unacceptable."

Iran responded angrily to the new EU sanctions Monday, with two lawmakers escalating threats that their country would close the Strait of Hormuz. Lawmaker Heshmatollah Falahatpisheh said Iran had the right to shutter Hormuz in retaliation and that the closure was increasingly probable, according to the semiofficial Mehr news agency.

"In case of threat, the closure of the Strait of Hormuz is one of Iran's rights," Falahatpisheh was quoted as saying. "So far, Iran has not used this privilege."

Some commentators are declaring that Iran should cut the flow of crude even before the new measures go into effect in July, to punish Europe, while others say the embargo is a "gift" which will allow the country to diversity its economy.

"Ineffective Western sanctions are not a threat to us, but an opportunity that has brought a lot of benefits," Moslehi said at a gathering in the central city of Isfahan late Monday.

The measures, approved in Brussels by the EU's 27 foreign ministers, include an immediate embargo on new contracts for crude oil and petroleum products. Existing contracts with Iran will be allowed to run until July.

Iran's Oil Ministry said the country can find new markets.

"Iran can easily find new customers for its oil," Mohsen Qamsari, a senior ministry official, was quoted by the semiofficial Mehr news agency as saying. "The National Iranian Oil Company has adopted the necessary measures to replace its oil exports in 2012."

Some 80 percent of Iran's foreign revenue comes from oil exports, and analysts say that any sanctions affecting its ability to export oil would hit its economy hard. With about 4 million barrels per day, Iran is the second largest producer in OPEC. It exports about 2 million barrels a day and consumes the rest domestically.

The EU has been importing about 450,000 barrels of oil per day from Iran, making up 18 percent of Iran's oil exports.

Some in Iran said the country should stop selling oil to Europe now, instead of July, to punish the bloc before it can find suppliers to replace Iranian crude oil in the midst of winter.

"The Iranian people now expect that the flow of black gold to Europe be cut before it can find a replacement for Iranian oil," state radio said in a commentary Tuesday.