(Reuters) - Axis Capital (>> Axis Capital Holdings Limited), a Bermuda-based speciality insurer and reinsurer, has raised its takeover offer for Lloyd's of London insurer Novae to about 477.6 million pounds ($611.38 million) after a shareholder revolt.

Novae Group agreed in July to be taken over by Axis Capital for 467.6 million pounds in cash, representing a 700 pence per share offer with a hefty premium to the London-based insurer's closing price from a day before the announcement.

But many shareholders said the offer undervalued the company, which covers property, casualty, marine, aviation and political risk. Late on Thursday, the two firms said they had agreed on a 715 pence per share offer.

"By offering Novae shareholders an improved cash offer, Axis aims to bring certainty to the transaction," Axis Capital said in a statement.

Novae's board had unanimously recommended the sweetened offer - which will create a roughly $2 billion player in the London speciality market - to its shareholders, Axis Capital said.

"We think the improved offer for Novae is a fairer reflection of the true value of the company," said Mark Martin, head of UK equities and manager of Neptune UK Mid Cap Fund, the top shareholder when the offer was announced, with a 16 percent stake. Neptune has drastically cut its stake since.

"We think there are relatively few other keen buyers in the market and would therefore be surprised to see a competitive bid situation arising."

Neptune said in July that the original offer undervalued the company, and a fair offer would be at least 5 or 6 percent higher than Axis Capital's initial bid.

Novae's shares have risen 20 percent since the offer in July. (http://bit.ly/2wDf0g3) On Friday, they were trading at 710 pence at 1129 GMT, up 1.8 percent.

"It’s still not an impressive price but MVN won’t stand in the way of the deal now," said a source close to shareholder London-based MVN Asset Management, the second-largest shareholder in Novae with 9.62 percent stake, according to Thomson Reuters data.

MVN voted against the previous deal in a proxy vote on Thursday, according to an email seen by Reuters. The proxy vote deadline was 1800 GMT on Thursday ahead of an extraordinary general meeting on Aug. 29.

MVN, Kite Lake Capital and Sand Grove Capital Management all converted holdings in Novae through derivatives to shares that gave them voting rights on Aug. 16, filings showed.

Gervais Williams, a fund manager at top-20 Novae shareholder Miton, said that income investors would also have been pleased by the increased offer in the light of the insurer's decision earlier this month not to pay an interim dividend.

"Normally they would have paid a dividend at this time of year of 7.5p and because they’re being taken over they’re not paying that dividend," Williams said.

"It’s very nice to get the takeover, don’t get me wrong, and it’s nice to get the premium, but you’ve got to meet your shareholders' expectations in terms of income."

Insurers have been preparing for a wave of mergers and acquisitions, as valuations in the Lloyd's insurance market became more attractive to overseas buyers due to a fall in the value of the pound after Britain voted to leave the European Union.

Lloyd's companies such as Hiscox (>> Hiscox Ltd), Lancashire (>> Lancashire Holdings) and Beazley (>> Beazley PLC) have long been seen as acquisition targets, and insurers Amlin, Brit and Catlin have all been snapped up by overseas insurers in recent years.

($1 = 0.7812 pounds)

(Additional reporting by Ben Martin, Carolyn Cohn and Helen Reid; Editing by Rachel Armstrong)

By Noor Zainab Hussain and Maiya Keidan