A deal for Dresser-Rand, which has a market capitalisation of more than $6 billion (3.68 billion pound), could come as soon as Monday, some of them said.

Siemens is expected to pay low- to mid-$80s per share, the sources said, compared to Dresser-Rand's Friday closing price of $79.91 which already had been boosted by takeover speculation in the past several days.

Discussions between the two companies are continuing and could still fall apart, the sources cautioned, asking not to be named because the matter is not public. A representative for Siemens declined to comment and a representative for Dresser-Rand could not immediately be reached.

Siemens, with its cash takeover bid, has trumped a competing offer from Swiss pump maker Sulzer AG, which proposed merging with Dresser-Rand in an all-stock deal, the sources said.

By acquiring Dresser-Rand, Siemens would get the company's compressors and turbines serving the oil and gas industry at a time when a North American drilling boom boosts demand for energy services and equipment.

(Reporting by Soyoung Kim in New York and Sophie Sassard and Anjuli Davies in London; additional reporting by Edward Taylor and Arno Schuetze in Frankfurt, editing by William Hardy)

By Soyoung Kim, Sophie Sassard and Anjuli Davies