Iran will make absolutely no concessions on its nuclear programme, a key lawmaker declared on Sunday amid high geopolitical tensions and ahead of mooted talks with world powers.

"The parliament will never allow the government to go back even one step in its nuclear policy," Aladin Borujerdi, the head of Iran's parliamentary foreign policy commission, told the official IRNA news agency.

Iran's recent announcements that is stepping up uranium enrichment and made its own 20-percent enriched nuclear fuel showed the country "totally masters nuclear science," he said.

"If the P5+1 countries don't accept the reality of Iran's nuclear abilities, they will suffer from that," Borujerdi was quoted as saying.

His comments precede expected talks agreed to by Iran and the P5+1 group of powers -- the five permanent UN Security Council members plus Germany.

Iran has formally requested a date and venue for the negotiations, the previous round of which collapsed in Istanbul in January last year.

The Islamic republic has been buffeted in recent months by ramped-up Western economic sanctions.

It has also been threatened with possible military action against its nuclear facilities by Israel and the United States.

Throughout, Tehran has maintained that its nuclear programme is purely peaceful, denying Western suspicions -- largely echoed in a November report by the International Atomic Energy Agency -- that it was conducting military research towards designing nuclear weapons.

Borujerdi told IRNA that the United States and its allies have seen in recent months that Iran's scientists have managed to make nuclear fuel enriched to 20 percent, among other achievements.

"Lawmakers expect the (Iranian) nuclear negotiating team to change the situation, to obtain a cancellation of (UN) resolutions (on Iran) and that the Iranian nuclear issue is taken from the Security Council and put back before the governors' board of the International Atomic Energy Agency," he said.

The remarks suggested Iran was taking a defiant negotiating position for the talks with the P5+1 -- one as hardball as the stance adopted by the United States and some of its allies, notably France and Britain.

US President Barack Obama has warned that Iran's leaders have to understand that "the window for solving this issue diplomatically is shrinking."

The US navy will have three aircraft carriers positioned near Iran in the coming days, and is doubling the number of minesweeping ships and helicopters based in the Gulf.

Israel, meanwhile, is keeping up rhetoric that makes many think the Jewish state -- the Middle East's sole if undeclared nuclear power, which is not involved in the talks -- is serious about possibly attacking Iran, with or without US support.

A majority of Israel's 14-member security cabinet now supports Prime Minister Benjamin Netanyahu in launching a pre-emptive strike on Iran in a bid to end its nuclear programme, the Israeli newspaper Maariv reported on Thursday, citing political sources it did not identify.

"Israel is very close to the point when a very tough decision should be made -- the bomb or the bombing," former military intelligence chief Amos Yadlin told reporters earlier this month.

The Western sanctions are taking a toll on Iran's vital oil exports, though to what extent is unclear amid competing declarations from Tehran and from Western agencies.

While shipments have certainly been curtailed to several markets, the tensions over the showdown have driven global oil prices higher, giving the Islamic state higher revenue per barrel of oil it manages to sell.