Chocolate maker Cadbury would reject a multi-billion takeover bid from US chocolate firm Hershey, it has been reported.

Cadbury, which employs 400 people at its Somerdale plant in Keynsham, has already described a hostile £9.8-billion offer from Oreos and Toblerone maker Kraft as “derisory” and is thought to be adamant there would be no deal unless a much higher bid is tabled.

According to the Sunday Times, Hershey, which is controlled by a charitable trust in Pennsylvania, is understood to be at an advanced stage of drawing up an offer.

This is thought to comprise of  $10 billion (£6 billion) in cash,  $2 billion (£1.2 billion) in new Hershey shares and between  £3 billion (£1.8 billion) and $5 billion  (£3 billion) from investors.

Hershey already has a business relationship with Cadbury, holding a licence to make Dairy Milk bars and Cadbury Creme Eggs in the US.

It is considered to be a better fit to Cadbury’s business and a counter bid could help the British chocolate maker trump the troublesome Kraft manoeuvre. But Cadbury is still adamant it wants to stay independent unless the price is right.

“We’re focused on delivering value to shareholders as a standalone pure-play confectioner,” a spokeswoman said today.

“However, we have always said that we would give proper consideration to any serious offer that delivers full value for the company.”

“Unless and until we find ourselves in that situation we have nothing to comment upon.”

There had been speculation that Hershey would team up with Italian confectioner

Ferrero to mount an offer but a report in the Wall Street Journal this weekend suggested Hershey had decided to go it alone.

Meanwhile, Royal Bank of Scotland has attracted the ire of MPs after it backed the Kraft offer.

Liberal Democrat treasury spokesman Vince Cable told the Observer that RBS should not be supporting a foreign company’s attempts to take over a British business.

“It is a scandal: this is not what a nationalised bank should be doing,” he said.

Cadbury began life as a grocer’s shop in Birmingham’s fashionable Bull Street in 1824. Dairy Milk is the UK’s top-selling chocolate bar and more than 250 million are sold every year in 33 countries.