TEHRAN, Iran (AP) - Iran has arrested three Americans for illegally entering the country from neighboring Iraq and a prominent Iranian lawmaker said Tuesday that authorities were investigating whether to charge them with spying.

A U.S. official rejected the allegation, and a security official in Iraq said the three were merely backpackers who got lost while hiking in a mountainous region where the Iran-Iraq border is not clearly marked.

The case is the latest source of friction with Washington over the detention of Americans, following the espionage trial earlier this year of American-Iranian journalist Roxana Saberi. Such a confrontation could be especially thorny this time around, when Iran is mired in its worst political crisis in 30 years over the disputed June 12 presidential election.