Image caption William Dartmouth (pictured far left) was asked about his involvement during a recording of Sunday Politics West, in May 2014

The deputy chairman of UKIP has been accused of lying publicly about his part in a proposed wind farm.

The BBC has learned the South West MEP Lord William Dartmouth was involved in negotiating a deal that could have earned his family £100,000 a year.

He was asked in a TV interview in May 2014 if he knew "that land might be used as a wind farm". He replied: "I don't know, um, no. No."

Lord Dartmouth said he was "ambushed" and spoke at "cross purposes".

His party is strongly opposed to onshore wind farms.

A deal to erect a wind farm, on Slaithwaite Moor in West Yorkshire, was agreed in May 2011, three months after Lord Dartmouth had given ownership of the site to a relative.

It has emerged negotiations over the wind farm had begun years earlier.

Steve Slator, chairman of the Wind Valley Co-operative, said he had face-to-face meetings with Lord Dartmouth, the first time in 2006.

"I went down and spoke to Lord Dartmouth who was very co-operative and keen to help us if he could.

"For this kind of area... you might expect to raise £50,000 to £100,000 a year for the sort of development you're looking at."

Image caption Lord William Dartmouth (left) did not want to comment about the wind farm allegations ahead of a BBC studio interview in May 2014

The news has been seized upon by his political rivals.

Molly Scott Cato, Green MEP for SW England, said there was "clear evidence" Lord Dartmouth has behaved "dishonestly" and people "expect higher standards" from politicians.

"It also does smack of hypocrisy; he had conversations about potentially benefitting from a wind farm development, in spite of the fact that's clearly contrary to UKIP's policy," she said.