Mumbai: Qatar has filed for regulatory approval to take a bigger stake in Nordic stock exchange OMX and said it was considering taking over the bourse, raising the prospect of a bidding war with Borse Dubai and its partner Nasdaq.

The Qatar Investment Authority (QIA) already claims a 9.98 per cent stake in OMX, just below the 10 per cent threshold at which the regulator must approve ownership.

Qatari prime minister Sheikh Hamad bin Jassim bin Jabr al-Thani, who also heads the QIA, said raising the stakes further was a serious possibility, though fraught with complications.

"I cannot say yes or no now but we are thinking about this seriously and ... you know there are a lot of complications in it but yes we are looking," he told CNBC television.

Qatar started acquiring stock in the Nordic and Baltic exchange owner just after Borse Dubai and US exchange Nasdaq announced they were teaming up to buy OMX.