Gulf of Mexico oil rig explosion could cost it £1.4 billion in net claims.

The specialist insurance market, which is made up of 78 underwriting syndicates, warned the estimates may vary but said it was unlikely there would be any call on its central fund as a result of the events.

It said net claims from the Chile earthquake earlier this year were in the region of £976.4 million, while the current estimate for claims from the Deepwater Horizon explosion is between £209.2 million and £418.4 million.

Lloyd's said loss information after a severe earthquake can take longer to obtain than from other events while the Gulf of Mexico situation is ongoing.

Chief executive officer Richard Ward said: "Clearly these events have had a significant impact on both Chilean and US-coastal communities, as well as a severe environmental cost in the case of the oil spill off Louisiana.

"Our priority remains to assess and settle valid claims as quickly as possible in both regions and helping to rebuild."

The update came as London's The Times said almost half the Lloyd's syndicates had launched a legal action in an attempt to block efforts by BP to claim on cover held by the rig operator Transocean.

The syndicates claim that BP's contract to lease the rig from Transocean specifies that its insurers would only be held responsible for damage to the rig itself - not for pollution caused by a leak from it.

BP said on Monday that the cost of the clean-up had hit £530 million.

The Lloyd's market has shown in recent years that it is more than able to cope with major catastrophes, including major hurricanes.

Among recent changes to modernise the market, Lloyd's introduced a new franchise structure and phased out the number of names who backed the market with an unlimited liability. And reflecting its focus on underwriting for profit, its combined ratio - the industry measure of profitability - is well below the level of 100 per cent that represents break-even.