The Tories will bring in a dedicated supermarket ombudsman if they win the next general election to “curb abuses of power by the major food retailers”.

Shadow environment secretary Nick Herbert will confirm the policy commitment in a speech today at the Oxford Farming Conference.

However, the new watchdog would be housed within the Office of Fair Trading rather that operating as a standalone body.

The move adds to pressure on the government to clarify its own plans for an ombudsman.

While the Competition Commission in August recommended that the body should be established, a government statement due in November was delayed pending further consultation with retailers. A decision is now expected this month.