Security forces have detained an American man for illegally entering Iran from Pakistan, state television reported Friday.

An Iranian police officer confirmed to The Associated Press the Tuesday arrest of the unidentified American, saying his motives for crossing the border had not been determined.

The American was being interrogated, the officer said, speaking on condition of anonymity.

Iran has tightened security on its eastern border with Pakistan and Afghanistan to prevent infiltration by supporters of the Al Qaeda (search ) terror group and the former Taliban regime in Afghanistan.

State television said the man was Jewish but did not identify him further. It said he was arrested in Sistan-Baluchestan (search ), a southeastern province that borders Pakistan.

American citizens are allowed to enter Iran provided they obtain a visa beforehand.

The United States severed diplomatic relations with Iran after militants stormed the U.S. Embassy in Tehran in 1979 and held its occupants as hostages for more than a year.

Relations thawed somewhat in the late 1990s but deteriorated in recent years after President Bush accused Iran of being part of the "axis of evil." Since the overthrow of Saddam Hussein (search ) last year, U.S. officials and the Iraqi defense minister have accused Iran of interfering in Iraqi affairs. Iran has denied the charge.

Iran has no relations with Israel and has called for its destruction. Conservative politicians routinely attack anything associated with Israel or Jews as "Zionist."