Iran's Foreign Ministry summoned Swiss ambassador to Tehran Philippe Welti yesterday to protest US spy activities in Iran, the official IRNA news agency reported.

Director General of Iranian Foreign Ministry's American department Ahmad Sobhani expressed "in its strongest terms " the Iranian protest over U.S. intelligence activities against Iran, IRNA said.

The Iranian intelligence ministry has discovered several spy networks in western, southwestern and central Iran, Sobhani said, adding that Washington is interfering in Iranian domestic affairs.

The Swiss embassy has been representing U.S. interest in Iran ever since Washington broke its diplomatic ties with Tehran in 1979

When Iranian protesters seized the U.S. Embassy in Tehran and kept 52 people as hostages for 444 days.

Sobhani said that Iran sought explanation from U.S. officials over the espionage matter, adding that such acts were a blatant violation of all international commitments on respecting other countries' sovereignty.

Welti promised to convey Iranian protest to U.S. officials, according to the IRNA report.