Activists climbed on to a roof at Buckingham Palace in a protest over fathers' rights.

Martin Matthews, 48, and Bobby Smith, 33, used a ladder to breach security after another campaigner caused a distraction outside the palace, a spokesman for the activists said.

They scaled the roof of the Queen's Gallery, a public art gallery at Buckingham Palace, at around 3.15pm and held a banner which read: "I am Harry's dad", according to the spokesman.

The demonstration is part of a joint campaign by the groups New Fathers 4 Justice and Stop The War On Dads. They have called for equal rights for fathers in divorce and separation proceedings and reform of the family courts.

A third activist, James Dennis from Bishops Cleeve, Gloucestershire, also attempted to scale the roof but is thought to have failed as security arrived, the spokesman said.

Speaking from the roof at the palace, Mr Matthews said he was aware of the risks he was taking, with heightened security concerns following the Paris terror attacks.

He said: “Obviously there were a few concerns. People are going to be nervous at the moment. But even if I had taken a bullet, it would have been worth the risk.”

Mr Matthews said he was able to climb on to the roof despite a number of police officers nearby and he was “delighted” the protest had raised awareness of his cause.

He said: “We parked a road away and came with a long ladder and walked past a number of armed policemen. They presumed we were workmen.”

A Palace spokesman said the incident was being handled by the Metropolitan Police and that the Queen and the Duke of Edinburgh were not in residence.

A Metropolitan Police spokeswoman said: "Police were called to a report of a protest taking place at the Queens Gallery at 4.28pm.

"Officers attended and two males were found to have climbed on to the roof of the entrance at the location.

"Officers are currently speaking with the people concerned. The incident is ongoing."

Mr Smith, from Stevenage, Hertfordshire, dressed as Sesame Street character Elmo when he stood against David Cameron in the Prime Minister's constituency of Witney, Oxfordshire, in the general election. The activist previously scaled Westminster Abbey on Father's Day.