PRAGUE/TRIPOLI (Reuters) - Up to 10 foreign workers are missing after a militant attack on a Libyan oil field and there is a possibility they have been taken hostage, Czech and Libyan officials said on Saturday.

Foreigners have increasingly become targets in Libya's turmoil, where two rival governments are battling for control and Islamist extremists have grown in the chaos that followed Muammar Gaddafi's ouster four years ago.

Czech Foreign Minister Lubomir Zaoralek said the workers missing after the assault earlier this week on Al-Ghani field, included a Czech and an Austrian and others from Bangladesh and the Philippines.

"We are examining the possibility that a kidnapping has taken place," Zaoralek told Reuters.

Libya's oil security forces said on Friday they had retaken control of the oilfield after Islamist militants attacked the facility, killing 11 guards. Several of those were beheaded, one official said.

Zaoralek said there had been no contact with any group claiming responsibility, adding that his ministry was certain the Czech citizen had not been killed during the attack.

Libya's state oil company said at least seven foreigners including an Austrian, a Czech, Filipinos and a national of an African country were missing after the al-Ghani attack.

"Foreigners from an Austrian oil services company, operating in the field, are still missing since the attack. We do not know their fate," National Oil Corporation spokesman Mohamed El-Hariri said.

In Vienna, a foreign ministry spokesman said a 39-year-old Austrian working for an oilfield management company had gone missing after an attack in Libya. He declined to give the name of the missing Austrian or his company.

Both the Czech and Austrian governments have assembled crisis groups to tackle the situation. A Czech official is expected to travel to the region soon.

Western governments are backing United Nations negotiations to end the crisis in Libya, worried that the large North African state just across the Mediterranean from mainland Europe is becoming a haven for Islamist militants.

Libyan militants claiming loyalty to Islamic State in Iraq and Syria have been blamed for high-profile attacks this year involving foreigners, including an assault on a Tripoli hotel and the beheading of a group of Egyptian Christians.

Militants this month also stormed and damaged several Libyan oilfields around al-Ghani, forcing the government to declare force majeure, pull out workers and shut down production on 11 oilfields in the central Sirte basin.

U.N.-backed talks to form a unity government and a lasting ceasefire in Libya are continuing in Morocco. But both sides face internal splits over the negotiations and fighting between the two governments continues.