An Irishman is among several workers taken hostage by a group claiming to be al Qaida at a gas field in Algeria.
It is reported that two people have been killed in the ongoing incident but it is understood the 36-year-old married man, from Northern Ireland, is unharmed.
Tanaiste Eamon Gilmore has called for the immediate release of the Irishman. "The Government stands ready to use all the resources available to us to ensure that our citizen is released as soon as possible," he said."I would ask that the family be allowed privacy at this difficult time."
The Department of Foreign Affairs said it was providing consular assistance to the family and was in close contact with its international partners and a wide range of other contacts in order to establish the facts of the situation.
A spokesman added: "At this stage, the identity and motives of the kidnappers is unknown."
One government source said the incident had all the hallmarks of a "political hostage taking", with the militants apparently keen to publicise the capture of foreign workers.
A British national caught up in the attack was killed, according to local reports. The UK's Foreign Office said British workers are involved in the incident at a BP oilfield near the border with Libya but officials could not confirm reports of the killing.
APS, the country's state news agency, said the Briton was the second person to die. A French national is also reported to have been killed during the raid, which comes after militant Islamists vowed to retaliate for France's military intervention, supported by British military equipment, against rebels in Mali.
Conflicting reports said there were between six and 20 people being held at the gas facility since the Islamist militants seized control. It is understood at least some of the captive workers were being kept within their own living quarters at the compound.
A news agency in the Saharan state of Mauritania was contacted by the militant group Katibat Moulathamine - "The Masked Ones" - with a claim that the attack was carried out by one of its affiliates, identified as "Those who sign their names in blood".