Iran says jets refused fuel in Europe
Iran says that some Western companies are refusing to refuel its planes in Europe, an act it says is illegal under international law.
Foreign ministry spokesman Ramin Mehmanparast warned that Tehran would "confront" such measures.
The UN imposed fresh sanctions on Iran in June for failing to halt its nuclear enrichment programme.
These were followed by punitive measures from some individual countries, including the US.
The US sanctions target Iran's energy sector, including products such as petrol and jet fuel.
Mr Mehmanparast, speaking at a news conference, was asked to comment on reports that flights by the state carrier Iran Air were being refused fuel at London Heathrow airport.
"Unfortunately, some Western companies have adopted inappropriate measures," Mr Mehmanparast said.
"We advise their governments that first of all this act is beyond the relevant regulations, even beyond those of the illegal UN Security Council's resolution, and under international law it is an unlawful act."
He added: "We will definitely not tolerate such inappropriate actions by some companies, and measures to confront such actions are on our agenda."
The Washington Post reported at the weekend that several major oil firms, including BP, Royal Dutch Shell and Q8, had cancelled fuel contracts with Iran Air.
It said the cancelled contracts had affected Iran Air flights departing from cities including Amsterdam, London and Stockholm.
They were now forced to make lengthy fuel stops in Germany or Austria where Total of France and OMV of Austria are still providing fuel, the report said.
The Iran Air website is issuing a warning to passengers that "due to ongoing fuel supply problems at London Heathrow" it might be necessary for London-Tehran flights to stop in Hamburg or Vienna, adding about 90 minutes to the journey.
It said talks to restore normal fuel supplies were taking place "as a matter of priority".