Stephen Hester
RSA chief Stephen Hester voiced his concern for the business in case of a BrexitGetty

Insurance company RSA's chief executive Stephen Hester has joined rival Lloyd's of London in voicing his concern about the effects a Brexit could have on his business' sector.

Hester came out in favour of a "remain" vote, telling Reuters the UK leaving the EU would do more harm than good to its business. Earlier in February, the company's competitor Lloyd's of London said it too supports remaining in the European Union (EU).

"Half of our market value comes from our European businesses, and in all of our markets, some of our major competitors are European," Hester told the newswire. "A level playing field between European competitors and ourselves is valuable to us in the long run."

The former RBS boss also said that leaving the EU would fuel market turmoil. RSA was among the 36 FTSE 100 companies which signed an open letter in the Times urging for the UK to vote against leaving the EU. The bosses of 200 big companies signed the letter.

Lloyd's also spoke out against a Brexit. Its chairman John Nelson was among the business leaders signing the letter to the Times and chief risk officer Sean McGovern gave a speech on 10 February explaining Lloyd's view on the EU referendum.

"It may be a statement of the obvious, but exiting the EU will create a level of uncertainty, for Lloyd's, for the London market, as well as the UK and European economies, we have rarely experienced," McGovern said.

McGovern also echoed Hester's concern regarding the European stock markets, saying : "A vote to leave would fuel European financial markets turmoil. [International Monetary Fund] managing director Christine Lagarde takes the view that a potential Brexit would cause turbulence for global financial markets and calls for a swift deal for the good of the European and world economies."

Lloyd's mentioned that, after the EU referendum in 1975, Lloyd's was relieved that the UK voted to remain in the EU.

"The position adopted by London insurers was in no doubt, and the majority vote for continuing membership evoked from the Lloyd's market feelings of delight, enthusiasm and, above all, relief," the company said at the time.