London-based BP Plc (NYSE: BP) (LSE:BP) confirmed that the major security incident at the In Amenas joint venture site in Algeria is continuing.
The In Amenas gas field and its facilities are operated by a joint venture of the Algerian national oil company Sonatrach, BP and Statoil.
"We have been informed by the UK and Algerian governments that the Algerian army is attempting to take control of the In Amenas site," the oil and gas company said.
BP said the situation on site remains unresolved and fragile. Armed groups still occupy the site and hold a number of site personnel.
A number of BP staff are among those held on the site, the company noted.
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"Sadly, there have been some reports of casualties but we are still lacking any confirmed or reliable information. There are also reports of hostages being released or escaping," the company said.
BP said it is in contact with the UK and Algerian Governments and added it would provide updates as soon as further confirmed information is available.
"As a precautionary measure, staged plans are underway to bring a group of non-essential workers out of Algeria," the company said.
U.S.-listed shares of BP added 0.11 percent to trade at $44.13 on Thursday.