A BID to trademark the shape of four-finger KitKats looks set to fail after being criticised by a senior European Court of Justice lawyer.

Nestlé, which produces up to six million of the bars a day at its factory in Haxby Road, York, said it would review Advocate General Melchior Wathelet's opinion that the appeal should be dismissed and was looking forward to the full decision of the court.

The former Belgian deputy prime minister said the move, which could see all other four-finger chocolate bars of the same shape and size in Europe made illegal, did not comply with European law.

Trademark experts said if the court ruled against Nestle, it could pave the way for a range of copycat bars to KitKat, the UK's best-selling confectionery brand.

They added it has raised questions of the future of the wafer bar, after which York City FC's stadium was named in 2005.

Nestle initially tried to protect the four-finger design, which has been produced at the plant since 1935, in 2010 by applying to register the four-finger wafer bar as a three-dimensional sign in respect of various chocolate-related goods.

The multinational firm, which employs about 1,800 workers at the plant, argued the bar's shape and snap had been associated with the firm for 80 years, and pointed towards a study which found 90 per cent of people linked an unbranded four-finger chocolate bar with Nestle.

Following Cadbury launching legal action to stop Nestle's trademark application, the High Court rejected the trademark proposal, leading the firm to appeal to the European Union court.

Simon Malynicz, a lawyer for Nestle, which saw its application to trademark the shape of the Polo mint thrown out by the Court of Appeal in 2004, told judges: “This is not a serious case about monopolising shapes at all.

“These cases have to be understood in the context of a long tradition in the UK of refusing registration to all shape trademarks, no matter how distinctive they have become."

After Mr Wathelet's statement, a Nestle spokesman said: "KitKat is much loved and its unique shape, which has been used for 80 years, is well known by consumers."

The announcement is the latest in a series of battles between Nestlé, the world's largest food firm, and Cadbury over trademarks, which has seen the companies fighting over whether the purple shade Pantone 2685C could be trademarked.