DUBLIN, June 11 (Reuters) - Some of the world's largest

aircraft lessors faced off against their insurers in a Dublin

courtroom on Tuesday at the start of a months-long battle over

around 2.5 billion euros ($2.7 billion) of insurance claims

related to jets stranded in Russia.

Lessors are suing dozens of insurers around the world over

losses of at least $8 billion after more than 400 planes were

prevented from leaving Russia when Western sanctions over

Moscow's war in Ukraine forced the termination of their leases.

The world's second and third largest lessors, SMBC and

Avolon, as well as BOC Aviation ( BCVVF ), CDB Aviation, Nordic

Aviation Capital and Hermes Aircraft, are pursuing their claims

in Ireland, where more than 60% of the world's leased aircraft

are owned or managed.

Lloyd's of London, Chubb and Fidelis are among the

insurers contesting the claims.

Insurers are balking at payouts, with some alleging that

there has not been a physical loss of the planes yet or that the

planes are still in the course of being repossessed. Others have

argued that lessors voluntarily ended leasing agreements or that

Western sanctions prevent insurers from providing cover.

The variety of arguments made by lawyers - including whether

the issue only relates to narrower "war risk" policies or also

to broader "all risk" insurance - are "bewildering and

confusing," Senior Counsel Paul Gallagher told the court in an

opening statement on behalf of four lessors.

"Insurers cannot agree on the meaning of their own

policies," said Gallagher, the first to speak in an opening by

lessors that is to run until June 19. The case is expected to

last around seven months.

The case is the largest ever heard in Ireland by number of

lawyers and is being held in a makeshift court as no courtroom

in the country is large enough to accommodate the 180 legal

professionals expected to attend each day, a courts service

spokesperson said.

On Tuesday, around 50 lawyers were allowed into a courtroom

in an open-plan office, with a similar number watching via a

video link in an adjoining former canteen.

The world's biggest aircraft lessor, Irish-based AerCap ( AER )

, is pursuing its insurance claims through London's High

Court, with what its lawyers have described as a "mega trial"

due to start in October. Other lessors have taken cases to the

United States.

Since launching their lawsuits, lessors have secured

settlements with Russia totalling more than $2.5 billion for

more than 100 jets, with ownership transferred to Russian

airlines.

($1 = 0.9298 euros)

(Writing by Conor Humphries

Editing by Mark Potter)