Indonesian President Joko Widodo has given the green light for Singaporean Lim Yong Nam to be extradited to the United States, to face charges there for breaching an American trade embargo against Iran.

Indonesia has no formal extradition agreement with the US, but cases can be considered individually. Mr Joko's approval comes months after Batam District Judge Cahyono granted the US request, based on statutes governing Indonesia's 1979 Extradition Law.

Riau police said the President's directive was issued earlier this year, and Lim is expected to be sent to the US soon.

The endorsement letter was sent recently to the Attorney's Office in Riau Islands province, said Lieutenant-Colonel Armaini of the local police force.

"It is the jurisdiction of the Riau Islands province's Attorney's Office now to decide the date of the extradition, but it wouldn't be too long from now," he said. The local police will take charge of security when the extradition process starts.

Lim is accused of acquiring 6,000 radio frequency modules for export to Iran. The US asked Singapore to extradite him in 2011, but Singapore's High Court found that the wrongdoing he was accused of was not an offence in Singapore.

Lim was apprehended by the Batam authorities in October 2014, after he went to the island to attend a trade exhibition. He has been held there since then.

In 2011, he was indicted along with three other Singaporeans and an Iranian national by the US Department of Justice for conspiring to allow electronics components from the US to be exported illegally to Iran instead of their stated final destination - Singapore.

The US alleged that 16 of the modules were found later in improvised explosive devices in Iraq that had not been detonated.

Lim's wife, Mrs May Lim, said yesterday she learnt about the Indonesian President's approval of the extradition about two weeks ago.

She told The Straits Times she visited her husband yesterday, and "he is very calm and waiting patiently for the extradition".

"The Indonesian authorities did not give me a specific date for the extradition, but I believe it will be soon," she said.

Expressing her disappointment that Lim would be sent to "a country so far away", she said: "Now, I just hope I can raise enough money to get counsel to represent my husband in the US."