TEHRAN, Iran — Iran’s supreme leader said yesterday that he was willing to restore diplomatic relations with America but that doing so now would make his country more vulnerable to American espionage.

“I would be the first one to support these relations,” state radio quoted Ayatollah Ali Khamenei as saying at a student group meeting in the central Iranian province of Yazd.

“Of course we never said the severed relations were forever,” Ayatollah Khamenei, 69, who has final say in all state matters, added. “But for the time being, it [restoring ties] is harmful, and we should not pursue it.”

Ayatollah Khamenei said restoring ties with America now would “provide an opportunity for security agents to come and go, as well as for espionage.”

“It has no benefit for Iranian nation,” state radio quoted him as saying at a student group meeting in the central province of Yazd. It would be an “opportunity for U.S. infiltration, traffic of their intelligence agents, and espionage on Iran.”

America and Iran have had no diplomatic ties since shortly after the 1979 Islamic Revolution, when militant students seized the American Embassy in Tehran and published sensitive documents they found inside documenting American intelligence-gathering in the country. The embassy, labeled the “Den of Spies,” is occasionally open to public as a museum documenting American misdeeds in Iran and the region.

The Swiss embassy in Tehran represents America in Iran, while the Iranians have an interest section in Pakistan’s embassy in Washington.

Iran last year claimed it had uncovered spy rings organized by America and its Western allies and detained four Iranian-Americans, who were later released. The arrests prompted America to warn its citizens against traveling to Iran, accusing authorities there of a “disturbing pattern” of harassment.

The dispute over Iran’s nuclear program and American allegations of Iranian support for armed groups in Iraq have further raised tensions.

Washington has refused to hold talks with Iran over the issue of diplomatic ties until Tehran suspends uranium enrichment, a process that can be used to produce fuel for both nuclear energy and weapons.

But the two countries have held three rounds of ambassador-level negotiations on security in Iraq, breaking the 28-year diplomatic freeze.

Iran says its nuclear program is intended solely for energy production, and Ayatollah Khamenei reiterated yesterday that his country would continue to pursue it to generate some 20,000 megawatts of electricity in the next two decades.