US naval forces in the Gulf attacked an oil tanker bound for an Iranian port on today injuring two people, Iran's state television reported.
Iran's foreign ministry summoned the Swiss ambassador, whose country represents US interests in Iran, later to deliver Tehran's strong protest and demand explanation.
A foreign ministry spokesman said the Saudi-owned tanker was carrying raw material for unleaded gasoline to the southwestern Iranian port of Abadan when it was intercepted by several US boats and seized.
He said the US had released the tanker after Iran lodged the protest.
A Pentagon spokesman, Lieutenant Colonel David Lapan, said a small explosive was detonated against a door to gain access to the tanker but no shots were fired during the encounter.
The television said earlier the Swiss envoy had told an Iranian Foreign Ministry official the US boats had mistaken the tanker for an Iraqi vessel smuggling oil.
US forces in the Gulf regularly intercept ships suspected of carrying Iraqi oil in violation of UN sanctions imposed on Baghdad for its 1990 invasion of Kuwait.
An Iraqi vessel sank last month after being boarded by US navy troops enforcing the sanctions in the region.
Tehran and Washington broke diplomatic ties after Iranian militants seized the US embassy in the Iranian capital in 1979 and took its staff hostage.