http://www.bbc.co.uk/news/world-middle-east-12729786Troops from a number of Gulf states, including Saudi Arabia and the UAE, have arrived in Bahrain at the request of the kingdom, officials say.
It comes a day after the worst violence since seven anti-government protesters were killed in clashes with security forces last month.
Dozens of people were injured on Sunday as protesters pushed back police and barricaded roads.
Bahrain's opposition said the foreign forces amounted to an occupation.
But the kingdom's authorities urged the population to "co-operate fully and to welcome" the troops, the AFP news agency reports.
'Answering request'
A Saudi official said about 1,000 Saudi Arabian troops arrived in Bahrain early on Monday, and later the UAE said it had sent some 500 police officers.
Witnesses told the Reuters news agency that about 150 Saudi Arabian armoured troop carriers plus other vehicles entered Bahrain on the causeway that links the two kingdoms.
The Saudi government said in a statement that it "has answered a request by Bahrain for support", according to the Saudi Spa state-run news agency.
The troops are part of a deployment by the Gulf Co-operation Council (GCC), a six-nation regional grouping which includes Bahrain, Saudi Arabia, Kuwait, Oman, Qatar and the United Arab Emirates.
It is believed they are intended to guard key facilities such as oil and gas installations and financial institutions.
