Bidders have begun submitting binding offers for DEA, the oil and gas production unit of German energy group RWE, and a deal could be struck as early as this month, people familiar with the matter have told the news agency Reuters.

"RWE is stepping up the pressure to get the sale done soon," one of the sources said, adding that the Essen-based group was already excluding DEA in its mid-term planning.

Some final bids for DEA are said to have already been submitted with the remainder expected this week. BASF's oil and gas exploration unit Wintershall, Russian tycoon Mikhail Fridman and Hungarian oil and gas group MOL are believed to be still in the race.

Cautious bids by a consortium of U.S. private equity firm KKR and Kuwait Petroleum Corp's Kufpec are regarded as unlikely to make the cut.

None of the purported bidders has been willing to comment. Hans Engel, BASF board member with responsibility for oil & gas, artfully dodged the question at the annual results press conference in late February. The German group, which has a close relationship with Russian gas giant Gazprom, is known to be willing to invest more in this business, which was the driver of its strong performance last year.

Financial details of the binding bids have not emerged, but one of the sources told Reuters that the range was expected to be similar to the first-round bids in the range of €3.5-5 billion.

With operations in 14 countries including Germany, the UK, Norway and Egypt, DEA employs nearly 1,400 people and accounted for about 9% of RWE's 2013 operating profit.

The company has stakes in about 190 oil and gas licenses or concessions in Europe, the Middle East and North Africa, some of which are non-producing and in need of large investments.