EU anti-trust regulators have given the green light for the merger of French giant Lafarge and Swiss rival Holcim to form the world's biggest cement group.

“Acquisition of Lafarge by Holcim is subject to conditions. The merger can proceed,” competition commissioner Margrethe Vestager said on Twitter on Monday, adding the move was “good for growth”.

The European Commission said it allowed the merger on condition Lafarge divest from businesses in Germany, Romania and Britain and Holcim sell its assets in operations in France, Hungary, Slovakia, Spain and the Czech Republic.

The commission said it had had concerns the “transaction as originally notified, would have” hurt competition in many markets in Europe but the two companies later addressed those concerns.

Holcim and Lafarge announced in April they were merging to create the world’s biggest concrete group worth 40 billion euros ($A60.00 billion), with an eye to booming construction in emerging markets.

The deal, a major event in the global construction industry, is based on the offer of one Holcim share for one Lafarge share.

The two groups together have a stock market value of 40 billion euros, Holcim chairman Rolf Soiron told a press conference at the time.

The new company will be called LafargeHolcim and “will have a unique position in 90 countries and will be evenly balanced between developing countries and countries with strong growth,” the firms said in a joint statement.

They highlighted the match of their activities since Lafarge has a strong presence in Africa and Holcim in Latin America.

However, they both have big and competing interests in Europe.