Eastgate Assistance has joined the Motoring Uninsured Loss Recoveries Association (MULRA) bringing its membership to 11.
The move means that more than 70% of ULR policies in the UK are now provided by MULRA members.
It follows last week's collapse of Manchester-based claims group Motor & Legal Group, which has boosted MULRA's call for higher standards.
MULRA chairman Paul Hurley said the Motor & Legal Group collapse may have repercussions for intermediaries and policyholders, as the intermediaries have endorsed a service without looking at the structure and financial security of the organisations.
He added: "In the continuing absence of a statutory framework for regulation, MULRA offers the only valid benchmark by which intermediaries and motorists can judge their ULR provider."
Eastgate Assistance's motor development manager Andy Tomkins said: "The industry needs to work together to encourage brokers to use recognised providers and stamp out the disreputable operators.
"Recent events have also demonstrated how important sound financial backing is to ensure consumers are protected. We are looking forward to working with all the MULRA members to achieve this."
Eastgate, which celebrates its 21st birthday this year, was accepted into membership after proving that it complies with the MULRA Code of Conduct.
To join MULRA, a company must have been trading in uninsured loss recovery for a minimum of three years.
It must also have paid up capital of at least £25,000, full insurance backing, current assets that exceed liabilities and at least £0.5m professional indemnity insurance.
The 11 MULRA member companies are: