They were renamed after the Iranian Revolution, and served in the Islamic Republic of Iran Navy during Iran-Iraq War.

The ships were built in the United Kingdom by Vosper Ltd and based on their Mark 5 design with the following arms & equipment:[1] They were refitted in the UK shortly before the 1979 Iranian Revolution.

After one was sunk, and other significant losses taken, during Operation Praying Mantis they saw little further use as the Iranian Navy proved no match for the U.S.

The Sea Cats were replaced by the addition of a 20 mm (0.79 in) AA gun.

[3] The Moudge-class frigate is a modified Iranian-built version of the Alvand class, with five either in service or under construction.