The Church Commissioners for England have sparked off a £1m legal battle over a restaurant fire blamed on a cleaning company.

Fire started at the Bombay Palace Restaurant in Connaught Street, London W1, as a result of grease dropping onto a gas burner on 16 April 2001, according to a High Court claim.

Although staff at the restaurant on the ground floor of an eight storey apartment block tried to fight the fire, they were unsuccessful, and the fire brigade spent three hours at the site.

Now the Church Commissioners, who own the site, and Readymight Ltd, trading as Bombay Palace Restaurant, have joined forces to sue ISS Food Hygiene Ltd, who supply kitchen and ventilation cleaning services.

They claim that ISS negligently failed to install baffle grease filters in December 2000 with reasonable care and skill, failed to put in collection drawers, and put them in at the wrong angle, so that grease could leak back onto the gas burner and ignite, the claim says.

ISS, of Woking, Surrey, also failed to clean extraction ducting properly in December 2000, and it was clear that at the time of the fire, there were large amounts of grease and fat up to 9cm deep in the ducting and hoods, the claim alleges.

The Church Commissioners and Bombay Palace argue that ISS made no proper attempt to clean or inspect the ducting before the fire. If access to the extraction ducting was restricted, ISS breached its cleaning contract by failing to draw that to their attention, and failing to recommend better access, the claim says.

The cost of remedial works, making the property safe, repairing the damage, and business losses amounted to more than £1m, the court will hear.

Before the fire, Bombay Palace's business was showing an upward trend, and its turnover between April 2000 and 2001 was about £940,000, with a gross profit of about 76.3%, the claim says. Bombay Palace puts its loss of profits at £290,589 for the 136 days it took to reinstate the restaurant.

ISS had been retained to carry out a six monthly deep clean of the extraction ducting, and fitted six baffle grease filters on the kitchen extraction hoods on December 12 2000, the claim says. ISS also went to the restaurant on 4 January 2001 to review and assess the ventilation system, the court will hear.