A Conservative peer at the centre of an internet frenzy over child abuse allegations has issued a vehement public denial of the "wholly false and seriously defamatory" claims against him.

Lord McAlpine, a former Tory treasurer and deputy chairman, has been the subject of intense speculation and innuendo since victim Steve Messham claimed last week he had been abused by a senior Conservative from the Thatcher era.

But the peer released a strongly-worded statement rejecting any suggestion that he had abused Mr Messham or any other residents of the Bryn Estyn home in Wrexham, North Wales.

He said he had visited Wrexham "only once", and that that had been in the company of an agent from Conservative Central Office. They visited a relative of Lord McAlpine's and did not stay overnight, he said.

"I have never been to the children's home in Wrexham, nor have I ever visited any children's home, reform school or any other institution of a similar nature," Lord McAlpine said.

"I have never stayed in a hotel in or near Wrexham, I did not own a Rolls-Royce, have never had a 'Gold card' or 'Harrods card' and never wear aftershave, all of which have been alleged. I did not sexually abuse Mr Messham or any other residents of the children's home in Wrexham."

Lord McAlpine said he had been defamed by "ill- or uninformed commentators" on the internet and "by innuendo" in the written and broadcast media, and warned that he may sue those responsible. A "substantial number of people" would have "reasonably inferred" that the allegations in the media had referred to him.

"Even though these allegations made of me by implication in the broadcast and print media, and made directly about me on the internet, are wholly false and seriously defamatory, I can no longer expect the broadcast and print media to maintain their policy of defaming me only by innuendo," he said.

"My name and the allegations are for all practical purposes linked and in the public domain and I cannot rewind the clock. I therefore have decided that in order to mitigate, if only to some small extent, the damage to my reputation I must publicly tackle these slurs and set the record straight."

His intervention came as the Guardian became the first newspaper to name him in connection with the allegations in a story suggesting he was the victim of mistaken identity. The paper quoted Wrexham councillor Keith Gregory, himself a victim of abuse at the Bryn Estyn, saying that he did not believe Lord McAlpine was involved in the scandal.