Bahrain's prosecution service said Monday it has charged 11 suspects with forming a "terrorist" group, including a number trained by Iran's Revolutionary Guards and the Hezbollah branch in Iraq.

The group, including four suspects on the run, has been charged with "establishing and joining a terrorist group; possessing explosives, weapons and firearms; and receiving training for terrorist purposes", Advocate General Ahmed al-Hamadi said.

He said four suspects "attended military training camps operated by Iran's Revolutionary Guards and the Iraqi branch of (Shiite movement) Hezbollah", although it was unclear if they were the fugitives.

The charges were filed after a probe into a weapons cache found in a warehouse in the Shiite village of Nuwaidrat, he said in a statement.

"In excess of 1.5 tonnes of high-grade explosives, including C4-RDX, TNT and other powerful chemical explosives were discovered in the counter-terrorism operation in September last year," he said.

The Sunni-ruled kingdom, home to the US Fifth Fleet, has witnessed unrest since the repression of a protest movement launched in 2011 by members of the Shiite majority demanding political reforms.

Bahrain has repeatedly accused Shiite-dominated Iran of meddling in its internal affairs, a charge denied by Tehran.

Scores of opponents have been detained, with many facing trial, while others convicted of involvement in violence have been handed heavy sentences, including loss of citizenship and life in prison.