In Iran, the Intelligence Minister Heydar Moslehi has called on Washington to propose a prisoner swap to secure the release of three US citizens arrested last July near the Iraq border. He said he had no doubt they were spies. Shane Bauer, 27, Sarah Shourd, 31, and Josh Fattal, 27, have been charged with espionage. Their families said they were hiking and strayed over the border accidentally. Tehran allowed the mothers of the three detainees to meet them last week, but ignored repeated pleas for their release. US Secretary of State Hillary Clinton has called for the three to be freed. The case has further strained relations between Washington and Tehran, which are at loggerheads over Iran's nuclear programme.