LONDON/COPENHAGEN (Reuters) - Independent oil exploration company Cairn Energy (>> Cairn Energy PLC) has emerged as the frontrunner for North Sea oil and gas assets put up for sale by DONG Energy (>> Dong Energy A/S), sources familiar with the matter said.

Interest from Cairn Energy and several other potential buyers could put pressure on shipping and oil group A.P. Moller-Maersk (>> AP Moeller Maersk A/S), after talks with DONG Energy to buy the oil and gas assets stalled at the end of last year. The two Danish firms had failed to agree on a price.

Final bids for the assets, which could be worth around $2 billion (1.60 billion pounds), are due by the end of February, the sources said.

Cairn Energy and DONG Energy declined to comment.

Cairn has 22 licenses in Norway, including two operating licenses, and 15 licences in Britain including one as operator, according to the company's website. Cairn also has some international projects, for example in Africa.

Several other potential bidders have emerged, although it was unclear whether they had or would bid for the assets. They include chemicals giant Ineos, private equity firm EIG Global Energy Partners, and oil and gas firm DEA, controlled by Russian billionaire Mikhail Fridman, the sources said.

DONG Energy said in November it would quit the oil and gas business to focus solely on offshore wind power.

One source said Maersk remained "in the picture" for the assets, but it was unclear whether the company still considered bidding.

Bringing together the two Danish companies' oil and gas divisions is still seen by many in the industry as a natural fit.

Maersk declined to comment.

DONG produced 89,000 barrels of oil and gas per day last year, down from 115,000 barrels daily in 2015. Its main producing assets include Ormen Lange in Norway, Syd Arne in Denmark and the Laggan-Tormore field in the United Kingdom.

Agreeing on a price has proven difficult, in part due to disagreements over who should pay for the decommissioning of some assets.

There is also uncertainty over an arbitration case between DONG Energy and a consortium of Technip and Daewoo Shipbuilding & Marine Engineering (>> Daewoo Shipbuilding & Marine Engineering) over who bears responsibility for construction errors concerning an offshore platform for the idled Hejre field.

(Reporting by Ron Bousso and Clara Denina in London, Jacob Gronholt-Pedersen in Copenhagen, Arno Schuetze in Frankfurt; Editing by Dale Hudson)