(Updates and recasts with European insurance bodies)
LONDON, June 20 (Reuters) - Twenty-one European insuranceassociations said on Monday it was in Britain's and the EuropeanUnion's interests for Britain to remain in the EU, and a Britishinsurance broking association said the sector would be betteroff if Britain remained.
Britain votes in a referendum on Thursday on whether toleave the EU.
The 21 trade bodies who signed an open letter released bythe Association of British Insurers (ABI) include those fromNorway and Switerland which are not in the European Union,although both countries are part of the EU's single market.
"The UK is an active and positive partner which also has afirm and critical eye and is willing to challenge as required,"the trade bodies said.
"This brings results for the UK, and is healthy for thewhole of the EU."
The ABI did not sign the letter but has also said Britainshould remain in the EU.
The British Insurance Brokers' Association, meanwhile,separately said on Monday it would be better for Britain toremain in the EU.
Brexit would lead to uncertainty for businesses, while alack of access to the "passporting" system enabling financialservices to be sold across Europe could reduce business forbrokers and choice for consumers, BIBA said in a statement.
"A Remain vote would stimulate investment and boostconfidence that we will be able to continue to trade freelyunder the EU freedom of services provision," BIBA chairman DavidHunt said in the statement.
Major insurers such as Lloyd's of London andLegal & General have previously spoken in favour ofBritain remaining in the EU.
U.S. insurer AIG said last week it may look for aEuropean headquarters outside London if Britain votedout.
But Dominic Burke, chief executive of broker Jardine LloydThompson, was among 110 signatories to a letter fromCity of London figures earlier this year backing Brexit. (Reporting by Carolyn Cohn; Editing by Jeremy Gaunt)