Malaysia is threatening to end free trade talks with the United States if it is asked to break an energy development deal with Iran.
Malaysia's prime minister Abdullah Badawi rejects US pressure
A US legislator has raised concerns about Malaysia's $16bn (£8bn) deal to develop Iranian gas fields and build liquefied natural gas plants there.
The US is Malaysia's biggest trading partner and free trade talks between them began in June last year.
Malaysia's prime minister says he will not bow to pressure from Washington.
Pressure on Iran
The US is trying to put pressure on Iran to end a nuclear programme that it claims is aimed at developing nuclear weapons.
Iran claims that it is only trying to generate nuclear energy.
Iran's president visited Malaysia last August
Concerns about trade between Malaysia and Iran were raised by Tom Lantos, chair of the US House of Representatives Foreign Affairs Committee.
But with a fifth round of trade talks between the US and Malaysia scheduled for later this month, Malaysian leaders warned they wouldn't allow its commercial relationship with Iran to impinge on negotiations.
"We reject the pressure being inflicted upon us... Do not bring any political matters into trade", state news agency Bernama quoted Abdullah Badawi as saying.
The two sides are under pressure to conclude the treaty because President George W Bush's fast-track authority on trade deals, through which he can ask Congress to conduct a single vote on any treaty without making amendments, expires at the end of June.