BRUSSELS (Reuters) - The EU antitrust regulator will reach a decision on U.S. data centre operator Equinix Inc's (>> Equinix Inc) 2.4-billion-pound ($3.7 billion) bid for British rival TelecityGroup (>> TeleCity Group Plc) by Oct.29, according to a filing on its website on Friday.

Equinix wants to boost capacity at its London operation and expand to Dublin, Milan and Warsaw, and the deal would make it the No. 1 data centre operator in Europe.

The European Commission - which is carrying out a preliminary review - could clear the deal, either with or without conditions. But if it has serious concerns, it could instead open a full-scale investigation.

The U.S. company sought EU approval for the deal on Sept. 24, according to the filing on the Commission's website.

The industry has seen a spate of mergers and acquisitions in recent months, with operators keen to expand their networks to attract multinational clients and tap into demand for cloud technology linking data from smart devices to remote servers.

Telecity dropped a $2.2-billion offer for Dutch peer Interxion Holding NV (>> InterXion Holding NV) following the Equinix bid.

($1 = 0.6567 pounds)

(Reporting by Foo Yun Chee; Editing by Pravin Char)

Stocks treated in this article : TeleCity Group Plc, InterXion Holding NV, Equinix Inc