* Sunni militants have taken much of north over past week
* Extra troops deployed around oilfields, drilling sites
By Ahmed Rasheed
BAGHDAD, June 16 (Reuters) - Iraq has tightened security and deployed extra troops around oil infrastructure and oilfields to help protect its vital energy industry from Sunni Muslim insurgents who have gained ground over the past week, a senior Iraqi security official said.
Brigadier Moussa Abdul-Hassan, chief of the South Oil Police, said additional troops have been deployed around oilfields, energy facilities, drilling locations and oil companies' headquarters.
Militants from the insurgent Islamic State of Iraq and the Levant have routed Baghdad's army and seized much of the north half of the country in the past week, threatening to break up Iraq and unleash all-out sectarian warfare.
"We have doubled security measures to keep oilfield operations and companies 100 percent safe. Now we have more than 100,000 oil policemen on ground on high alert, ready to protect energy facilities in the south," Hassan told Reuters.
"We formed a crisis cell to closely monitor the security of foreign oil companies and we assured companies ... that their security is our top priority."
Iraq looks to its massive oil resources for its future stability and prosperity, but still confronts a resilient Sunni Islamist insurgency now pushing southward towards Baghdad.
Iraq's mainly Shi'ite south, where the majority of the oilfields being developed by foreign firms are located, has been relatively safe and stable for the past two years.
"The checkpoints and protection posts were almost doubled and oil police members have been equipped with more powerful weapons, including rocket-propelled grenades and rifles," Hassan said.
Basra, the main city in the far south at the edge of the Gulf, has enormous strategic importance as the hub for oil exports accounting for over 95 percent of government revenue.
Hassan denied rumours that foreign oil workers were being evacuated from Basra and said work is going on smoothly at oilfields around the city.
Officials from the state-run South Oil Co. (SOC) also said operations in the southern oilfields are normal and none of the foreign companies have informed them of any evacuation plans.
"Basra is safe as always. Somebody is trying to muddy waters by saying foreigners are leaving," said a senior SOC official.
Iraq is now dependent on oil exports from the south after Sunni militants attacked the northern Kirkuk-Ceyhan pipeline in March. (Additional reporting by Mohammed Atti in Basra; Editing by Oliver Holmes/Mark Heinrich)