Cadbury Schweppes yesterday tested the appetite of rival confectionery firms for Butterkist popcorn after putting the 67-year-old brand up for sale.

The company, which earlier this year overtook Mars to become the world's biggest selling confectioner, said it was open to offers for the Monkhill business that makes the brand.

Monkhill generates around #80 million each year from sales of Butterkist, smaller brands such as Sharp's and the supply of sweets to supermarkets to sell under their own names.

Butterkist dates back to 1938 in the UK although popcorn machines carrying the same name were in circulation in the United States more than 20 years earlier.

It was bought by Cadbury from Craven Keiller in 2000 and popping pans were set up at its factory in Pontefract where 5,000 tonnes of popcorn are produced each year.

Butterkist was relaunched in 2002 and had captured a 44 per cent share of the UK market for popcorn which was worth #24 million in 2004.

Cadbury said the Monkhill business included four manufacturing plants at Pontefract, York, Cleckheaton in West Yorkshire and Leeds, along with a depot at Holmewood, near Sheffield.

Around 800 staff will transfer to new owners at the end of a sale process being handled by investment bank Investec. Cadbury, which employs a large workforce at its plant in Bournville, said it expected the business to be sold before the end of this year.