Bauer, left, and Fattal, are still awaiting trial, nearly two years since their arrest in July 2009 [AFP]

Iran has postponed the expected trial of two Americans being held in the country on spying charges for nearly two years, according to their lawyer.

Masoud Shafiei, the Iranian lawyer for Shane Bauer and Josh Fattal, said the two were not brought into court on Wednesday.

Shafiei said Iranian officials gave no immediate explanation. The US state department earlier called on Tehran to quickly resolve the case.

"We urge Iran to resolve this case as soon as possible. Josh Fattal and Shane Bauer have been in prison for almost two years, and it's time to reunite them with their families," Mark Toner, the state department spokesman, told reporters late on Tuesday.

"We understand from our Swiss protecting power that Iranian authorities have confirmed Wednesday as the new trial date," Toner said.

Switzerland looks after US interests in Iran because the United States and Iran do not have diplomatic relations.

Plea for legal access

Fattal, Bauer, and American Sarah Shourd were arrested by Iranian forces on July 31, 2009, on suspicion of spying after allegedly crossing into Iran from Iraq's Kurdistan region.

Shourd, who was released on $500,000 bail in September and returned home, has said they were hiking and had never intended to cross into Iran.

Shourd, freed on bail after being held on suspicion of espionage, has said they were innocent hikers [EPA]

Iran delayed an earlier hearing that had been scheduled to start in November 2010.

"We, obviously, urge Iran to permit Josh and Shane unfettered access to legal counsel and immediate consular access by the Swiss protecting power," Toner said.

Swiss intermediaries last visited the detained Americans in late October, he said.

In Tehran, Shafiei earlier said it was unlikely that Shourd would return for the hearing.

Under Iran's Islamic law, espionage can be punished by execution.

The case has further complicated relations between Iran and the US, which are strained over Iran nuclear program.

Washington accuses Tehran of pursuing nuclear weapons. Iran says its nuclear programme is for peaceful purposes.

Source: Agencies