OMX Chairman Urban Backstrom said Borse Dubai's all-cash bid was not more attractive than Nasdaq's share-and-cash bid and called it hostile, newspapers reported on Monday.

Backstrom said the industrial synergies from the Nasdaq offer were higher than any from Borse Dubai, though OMX had yet to decide which bid to back, the Wall Street Journal reported.

The Nordic exchange owner is uneasy about being owned by the Dubai government.

I could never have realized then that another state, a sovereign state, would put a bid in (for) the company, the Wall Street Journal quoted Backstrom as saying. Backstrom worked in the Swedish Ministry of Finance when the country was privatizing the Swedish stock market in the late 1990s.

There are many ways to build confidence, but what is going on is quite strange. Usually you get a phone call the day before a bid is made, but this time I had to read about it on the (Web), newspaper Dagens Nyheter quoted Backstrom as saying.

It is clear that Borse Dubai does not care about OMX board's view, and therefore the bid must be seen as hostile.

OMX's shareholder Investor AB, with 10.7 percent stake, also said it was not obvious that Borse Dubai's bid was more attractive than Nasdaq's bid.

Given the industrial logic we identified in a transatlantic cooperation, the level of Borse Dubai's cash bid is not sufficiently attractive, Swedish newspaper Dagens Nyheter quoted Fredrik Lindgren, a spokesman for Investor AB.

Borse Dubai's cash offer on Friday trumped an agreed $3.7 billion cash and share deal with Nasdaq. Sources familiar with the matter said last week Nasdaq Chief Executive Bob Greifeld planned to travel to Sweden this week to meet management and stakeholders in OMX.

Borse Dubai said it controlled 28.4 percent in OMX if its options in OMX shares were exercised.