Margaret Thatcher's former PR chief has criticised Theresa May's labelling of the Conservatives as "the nasty party".

Lord Tim Bell, who has been brought back to advise the party by leader Iain Duncan Smith, said May's famous conference speech had been "very damaging".

Bell's comments to the BBC on Sunday are likely to renew tensions between Duncan Smith's supporters and May, who is Conservative Party chairman.

"I think the 'nasty party' was most unfortunate and very damaging," he told the Breakfast with Frost programme.

"Obviously it was taken out of context but it was unfortunate because it appeared we thought that we ourselves are nasty rather than just the people who oppose us do."

Relations between May and Duncan Smith have been frosty since the row over his decision to sack a key aide at Central Office and replace him with a former MP.

May backed the party's executive over the decision to appoint Barry Legg and the row, which generated embarrassing headlines, ended with a partial climb down by Duncan Smith.

The comments by Bell, who has been brought back by Duncan Smith alongside the party's advertising guru Lord Saatchi, were followed by a rebuttal of claims May is set to be sacked.

"Iain Duncan Smith has made it clear that there will be no Shadow Cabinet reshuffle this year," a spokesman said.