Iran's president has said he will not back down over Tehran's nuclear programme, despite the threat of referral to the UN Security Council.
Ahmadinejad defended Iran's right to nuclear energy
In his first public reaction since European ministers called for the UN's involvement, Mahmoud Ahmadinejad said Iran would not concede "one iota".
Earlier, Iran threatened to halt snap inspections of its nuclear sites if it was referred to the Security Council.
Iran denies claims it is covertly seeking to develop nuclear weapons.
The crisis intensified this week when Iran removed seals at three nuclear facilities, ending a two-year freeze. Tehran says it plans to resume nuclear fuel research.
On Thursday, the UK, France and Germany said talks with Iran had reached a "dead end".
IRAN'S NUCLEAR STANDOFF
Sept 2002: Work begins on Iran's first reactor at Bushehr
Dec 2002: Satellites reveal Arak and Natanz sites, triggering IAEA inspections
Nov 2003: Iran suspends uranium enrichment and allows tougher inspections
June 2004: IAEA rebukes Iran for not fully co-operating
Nov 2004: Iran suspends enrichment under deal with EU
Aug 2005: Iran rejects EU plan and re-opens Isfahan plant
Jan 2006: Iran re-opens Natanz facility
They called for an emergency meeting of International Atomic Energy Agency (IAEA) - the UN's nuclear watchdog - which can refer Iran to the UN Security Council, which in turn can impose sanctions.
BBC diplomatic correspondent Bridget Kendall says the Europeans' top priority is a lobbying campaign to convince other nations - especially non-aligned countries and Iran's key partners Russia and China - that the time has come for a new and tougher approach.
On Friday, China's UN ambassador Wang Guangya warned that referring Iran to the Security Council "might complicate the issue".
"I think this might make the positions of some parties more tough on this issue," Mr Wang told reporters at the UN.
Earlier, UK Foreign Secretary Jack Straw told the BBC the dispute could "only be resolved by peaceful means".
He said sanctions would be considered, although other measures would be taken first.
Russia has not ruled out a referral, but says not all diplomatic steps have been taken.
European, Russian, Chinese and US officials are due to meet in London on Monday when they are expected set a date for the crucial IAEA meeting.
Iran 'not frightened'
Speaking in the southern Iranian town of Bastak on Friday, President Ahmadinejad defended his country's nuclear programme.
"Iran is not frightened by the threat of any country and it will continue the path of production of nuclear energy," state radio quoted him as saying.
"The government will not back down one iota on defending people's rights," he said.
He complained of a bullying attitude on the part of Western countries, saying they claimed to be protecting world peace but were lying because they possessed nuclear arsenals themselves.
Earlier, Iranian Foreign Minister Manuchehr Mottaki said Iran would "be obliged to end all... voluntary measures" if sent to the Security Council.
The move is in keeping with a recent Iranian law obliging the government to pull out of the Nuclear Non-Proliferation Treaty's (NPT) "additional protocol" in the event of a referral to the UN.
The protocol allows intrusive and short-notice inspections of Iran's nuclear sites, which UN inspectors see as key to supervising the programme.
Iran is also observing a self-imposed ban on uranium enrichment, which under certain conditions can produce the fuel for nuclear bombs.
Following the EU ministers' statement, UN Secretary General Kofi Annan said Iran's chief nuclear negotiator told him Iran was still interested in "constructive negotiations, but within a time-frame".
Mr Annan said he was keen for the issue to be resolved through the IAEA, if possible.