American International Group Inc Share News (AIG.US)

LONDON, Sept 16 (Reuters) - Western insurers on Tuesday lost a London High Court bid to appeal against a judgment that hands aircraft lessors $1.0 billion-plus from their war risks insurance policies to cover the loss of jets stuck in Russia since the invasion of Ukraine.

Judge Christopher Butcher told the court he was refusing permission to appeal on all grounds but would reach a final decision in relation to who bears which legal costs at a later date.

Butcher in June ruled that aircraft lessors such as AerCap , which were suing insurers for billions of dollars over the loss of almost 150 aircraft and some engines, can recover costs under war risks policies. But he blocked AerCap's hopes of securing a higher payout under its uncapped all risks cover.

The decision marks another milestone in one of the largest lawsuits to be heard in London, which has become a bellwether for similar cases fought in other jurisdictions, such as the United States, and triggered a battle in London between all risks and war risks insurers over who should pay which costs.

Lawyers for Ireland-based AerCap, the world's largest lessor and the biggest claimant in London, said their legal expenses alone ran to around 81 million pounds ($111 million), court filings show.

Lessors AerCap, Dubai Aerospace Enterprise, Merx Aviation, KDAC Aviation Finance, Falcon and Genesis had led the claims against a string of insurers, including AIG, Lloyd's, Chubb, Swiss Re and HDI Global Specialty.

The lawsuit had focused on almost 150 jets and some engines, valued at up to $4.7 billion. But settlements, including on the first day of the trial last October, whittled the numbers down.

KDAC settled all its claims during the trial, Butcher has said, while AerCap struck a deal with Swiss Re and HDI, DAE settled with all war risks insurers and Merx settled with all war risks insurers apart from Fidelis, court filings show.