MANAMA (AFP) - Armoured troops rolled into Bahrain from neighbouring Saudi Arabia on Monday to help restore order in the strategic Gulf kingdom, where pro-democracy demonstrators have shut down the financial centre. Thousands of mainly Shia protesters occupied Manamas business district, turning the regional banking hub into a ghost town as they pressed their calls for democratic change from the Sunni Muslim monarchy. The Saudi government said it had responded to a call for help from its neighbour as Saudi-led forces from the Gulf countries joint Peninsula Shield Force crossed the causeway separating the two countries. The council of ministers has confirmed that it has answered a request by Bahrain for support, the Saudi government said in a statement carried by the SPA state news agency. It said that under an agreement of the six-country Gulf Cooperation Council (GCC), any harm done to the security of a member state is considered a harm done to the security of all members. The exact make-up of the force was not known, but the United Arab Emirates also confirmed it was participating in the operation. The GCC groups Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the UAE. The United Arab Emirates has sent around 500 police to neighbouring Bahrain amid escalating anti-regime protests there, Emirati Foreign Minister Sheikh Abdullah bin Zayed al-Nahyan said on Monday. The Bahrain government asked us yesterday to look at ways to help them to defuse tension in Bahrain, Nahyan told journalists when asked about the UAE decision to send security forces in. We have already sent roughly around 500 of our police force who are there, he said at a gathering of Group of Eight foreign ministers in Paris, where the UAE is representing the Gulf Cooperation Council. Television footage showed convoys of unmarked, desert-brown coloured armoured vehicles crossing the causeway from Saudis Eastern Province into Bahrain, the home of the US Fifth Fleet. The Shia-led opposition alliance said any foreign force would be treated as an invading army. We consider the arrival of any soldier, or military vehicle, into Bahraini territory... an overt occupation of the kingdom of Bahrain and a conspiracy against the unarmed people of Bahrain, said an opposition statement. Helicopters buzzed overhead as protesters blocked access roads to the Financial Harbour business complex, a day after more than 200 people were injured there in clashes between riot police and demonstrators. Sunday was the worst day of violence in the tiny Gulf kingdom since seven people were killed at the start of anti-regime unrest a month ago. Protesters persisted with a sit-in at nearby Pearl Square, where activists were readying for a showdown with the security forces. Most workers seemed to be following a trade union call for a general strike to protest against violence by the security forces. On Monday, US National Security Council spokesman Tommy Vietor urged the Gulf states to show restraint and respect the rights of the people of Bahrain, and to act in a way that supports dialogue instead of undermining it. In a major concession to the opposition demands, Crown Prince Salman on Sunday said he supported the creation of a parliament with full powers and pledged to tackle corruption and sectarian tensions. Foreign Minister Khalid Al-Khalifa, in comments posted Monday on Twitter, accused the opposition of shifting their demands and likened the protesters to gangsters. Iranian Foreign Minister Ali Akbar Salehi on Monday demanded that Bahraini leaders be wise and not use violence in their handling of anti-government protests, the state-run Fars news agency reported. The United States warned Gulf states on Monday to respect the rights of the people of Bahrain, after Gulf troops crossed into the violence-wracked kingdom. National Security Council spokesman Tommy Vietor said that the White House was aware that Saudi Arabia had sent security forces to Bahrain and that other Gulf Cooperation Council nations were also planning such steps. We urge our GCC partners to show restraint and respect the rights of the people of Bahrain, and to act in a way that supports dialogue instead of undermining it, Vietor said.