DUBAI (Reuters) - An Iranian man accused of violating U.S. sanctions and detained in Germany has been freed and has returned to Iran after diplomatic efforts by Tehran, Iran's foreign ministry spokesman said on Monday.

The man, Ahmad Khalili flew home with Iranian Foreign Minister Mohammad Javad Zarif, who had been in Germany to attend the Munich Security Conference, Iranian state TV quoted spokesman Abbas Mousavi as saying.

German authorities declined to comment on the case.

"Mr. Ahmad Khalili, an Iranian citizen, who was arrested in Germany at the request of the (U.S. Justice Department) and subject to extradition to America under the excuse of violating the illegal and cruel sanctions of America was freed last night and returned to the homeland with the minister of foreign affairs," said Mousavi, according to state TV.

The spokesman did not say how Khalili might have violated U.S. sanctions but said he had been freed through "intense diplomatic consultations and with the effective cooperation of the (Iranian) judiciary and the intelligence department of the Revolutionary Guards".

Mousavi did not elaborate on how Iran's judiciary or the intelligence wing of the elite Guards, the most powerful military force in Iran, had contributed to the decision to free Khalili.

Tensions between Iran and the United States have escalated since the Islamic Republic's most prominent military commander, Qassem Soleimani, was killed in a U.S. drone strike in Baghdad on Jan. 3. Iran retaliated with a missile barrage against a U.S. base in Iraq days later.

U.S. President Donald Trump withdrew from a 2015 nuclear deal between Iran and six powers in 2018 and Washington reimposed sanctions which have battered the Islamic Republic's economy.

A Chinese-American detained in Iran in 2016 and later charged with spying was freed in December and an imprisoned Iranian was released by Washington in return, and both were flown back to their countries.