The United States has urged Saudi Arabia to show restraint, after it sent troops into neighbouring Bahrain.

Some 1,000 troops from Saudi Arabia and a further 500 from the United Arab Emirates arrived in Bahrain on Monday at the invitation of the government.

According to the opposition leader, the influx of foreign forces amounts to an occupation.

The BBC's Caroline Hawley in Manama says that unarmed protesters have told her they are ready to confront the foreign forces "with their empty hands".