Starbucks has been criticised for quietly changing its logo over the last few weeks to make it more sexually appealing.

The coffee chain has turned the abstract illustration of part of a mermaid into a full picture of a bare-chested siren with open legs.

A US Christian group called The Resistance has hit out at the sexual nature of the logo and called on its 3,000 members to boycott the stores, referring to the company as “Slutbucks”.

Starbucks, however, has said that it will go ahead with plans to replace the old logo with the updated version on its cups and on bags of some of its coffee within the next few weeks.

The new logo is a based on the one the company used when it opened its first site in Pike Place in Seattle in 1971.