The king of Bahrain has declared a state of emergency, due to start immediately and which will last for three months, state TV has reported. The announcement follows weeks of unrest in the kingdom. The nation's armed forces chief has been authorised to take all measures to "protect the safety of the country and its citizens", says the statement from the king. On Monday, forces from Gulf countries arrived to bolster the regime. Some 1,000 troops from Saudi Arabia and a further 500 from the United Arab Emirates deployed in Manama at the invitation of the government. It is believed they are intended to guard key facilities such as oil and gas installations and financial institutions. The US State Department has urged its citizens to avoid travelling to the country due to the ongoing unrest.