BRUSSELS, May 2 (Reuters) - The aborted merger of oilfield services provider Halliburton and smaller rival Baker Hughes had raised significant competition concerns in Europe, EU Commissioner Margrethe Vestager said on Monday.

The Commission said it took note of the companies' announcement that they had abandoned their proposed merger, adding this followed concerns by competition agencies around the world, including the Commission.

"In this case, based on the Commission's in-depth analysis, the transaction raised competition concerns on a very large number of markets related to oilfield services provided to oil and gas exploration and production companies in the EEA," Vestager, who is in charge of competition, said in a statement.

"In this regard, a number of customers contacted us to raise issues with the proposed transaction," she continued.

It added that its investigation had been carried out in close cooperation with a number of competition agencies such as the U.S. Department of Justice, the Brazilian CADE or the Australian ACCC.

(Reporting By Philip Blenkinsop; editing by Robert-Jan Bartunek)