Six workers from a Polish oil and gas surveying company have been kidnapped in northwestern area of the country, military sources told Reuters, years after a Polish engineer from the same company was beheaded by Pakistani militants.

The six Geofizyka Krakow workers were snatched on Saturday afternoon from their vehicles on a road near the village of Drazinda, some 80km (50 miles) from the northwestern area of Dera Ismail Khan , two military officials with security forces in the area said on condition of anonymity as they are not authorized to speak to the media.

One of the sources provided Reuters with the names and national identity card numbers of the workers.

Geofizyka Krakow, which is a subsidiary of Poland's state-run gas firm PGNiG, could not be immediately reached for comment. On its website, the company said it had entered liquidation in August 2016.

No militant group has claimed responsibility for the kidnappings. In the past, militants from the hardline Islamist Pakistani Taliban group have kidnapped people in the region for ransom or to bargain for the release of prisoners.

The area where the workers were kidnapped is close to South Waziristan, part of the Federally Administered Tribal Areas (FATA) bordering Afghanistan.

Geofizyka Krakow has a long history of conducting seismic services in Pakistan.

In 2008, a Polish engineer working for the firm was kidnapped by the Pakistani Taliban near the northwestern city of Attock, and beheaded several months later.

Overall security in the country has improved over the last few years but many of the northwestern areas bordering Afghanistan remain volatile and dangerous, especially for foreigners and those working with foreign companies.

The frontier regions, deeply conservative and hard to access due to rough terrain, have long been the sanctuary of fighters from al Qaeda, the Taliban and other militant groups.

Most of the myriad militant groups that stage attacks inside the country seek to overthrow the government to establish an Islamic theocracy and impose a stricter interpretation of the religion than is practised in much of the country