NEW YORK (Reuters) - Activist investor ValueAct Capital vowed to fight a lawsuit brought against it by the U.S. Department of Justice on Monday over its role in the $35 billion merger of oilfield service provider Halliburton Co's (>> Halliburton Company) and Baker Hughes Inc (>> Baker Hughes Incorporated).

ValueAct said it will "vigorously" defend its position.

The Department of Justice said earlier on Monday it had sued ValueAct Capital for violating pre-merger notification requirements related to Halliburton's deal to buy rival Baker Hughes.

(Reporting by Michael Flaherty)

Stocks treated in this article : Baker Hughes Incorporated, Halliburton Company