At least 57 people have been killed in the past two weeks from flash floods after the worst rains in Iran in at least a decade, Iranian government officials said.

Iranian authorities have ordered the evacuation of 70 villages in Khuzestan province near the Dez and Kharkheh rivers due to flood risk, according to state-run IRNA news agency.

The announcement comes a day after Iran's Foreign Minister Mohammad Javad Zarif blamed sanctions imposed last year by US President Donald Trump's administration for hampering rescue operations in flood-stricken areas of the country, where 45 people have died so far.

"America's 'maximum pressure' policy on Iran is impeding aid efforts by IranianRedCrescent to all communities devastated by unprecedented floods," Zarif said in a Twitter post on Monday night.

The sanctions, he said, have prevented Tehran from getting badly needed equipment, including relief helicopters.

"This isn't just economic warfare; it's economic TERRORISM," he said.

Local authorities in the stricken areas have repeatedly asked for more helicopters to reach remote and cutoff locations. 

Britain and Germany have offered to send help, including boats and safety equipment.

Iranian media reports said the floods have cut off some 80 inter-city roads, as well as roads to nearly 2,200 villages, and that electricity and communications with many places, including in western Ilam and Lorestan provinces, have been cut.