South Korea's defence agency has ordered companies to suspend tear gas exports to Bahrain following pressure from human rights groups.

The state-run Defence Acquisition Programme Administration instructed two companies not to ship tear gas to the Gulf state after they had inquired about possible exports, agency officials said.

Both companies exported tear gas to Bahrain in 2011 and 2012, but the exports now need state approval because a key ingredient is listed as a strategic material in South Korea.