Troops from the Gulf Cooperation Council's Peninsula Shield Force will remain in Bahrain even after emergency laws are lifted next month, Gulf News reports.
Iran has condemned the 1,500-strong Gulf Arab force's presence in Bahrain as an "occupation" by Sunni Gulf monarchies against Bahrain's Shiite majority.
In response, Gulf leaders have warned Iran to stay out of their affairs and accused Bahrain's protesters of having links to groups such as the Iranian-backed Hizbullah militants in Lebanon.
Bahrain's military chief, Sheikh Khalifa bin Ahmad Al Khalifa, also threatened harsher crackdowns if demonstrators return to the streets. "I say to those who did not get the message, 'If you return we will come back, stronger this time,'" Al Khalifa told the official Bahrain News Agency on Wednesday.
Khalifa further claimed protesters were "given pills which affected their minds and made them do unusual things."
A similar allegation was made by Libyan leader Moammar Gaddafi who said his opponents included young people on hallucinogenic pills placed "in their coffee with milk, like Nescafe."
Bahrain's King Hamad ignored a request by parliament to extend emergency rule saying it would be lifted June 1. But the military chief's statements suggest a heavy security presence will remain along with GCC troops.
Bahrain is home to the US Navy's 5th Fleet.