The Second Severn Crossing, the main road link between Wales and England, was closed by police yesterday after it was occupied by Fathers 4 Justice protesters dressed in Santa Claus outfits.

Three men and a woman scaled a gantry of the M4 bridge and three more protesters climbed buildings in Cardiff Bay.

A few hours later two men also campaigning for Fathers 4 Justice and dressed in Santa costumes climbed the Pierhead Building in the bay. Another was found climbing a disused former Post Office building.

The protests happened shortly before a visit to the Wales Millennium Centre in the city by the Queen, the Duke of Edinburgh and the Prince of Wales.

The centre took out a high court injunction against Fathers 4 Justice on Friday to prevent them targeting its opening ceremony.

"We have four Santas on the gantry on the south Wales side of the bridge," a Fathers 4 Justice spokesman told the BBC.

"They wanted to give the Queen a good welcome to Wales. We didn't want to cause too much disruption to the public; that's why we have done it on a Sunday."

The group has organised a Christmas campaign to renew pressure on behalf of divorced fathers. It wants an automatic half-half division of parental access.

Last week David Pyke, 49, dressed up as Santa and handcuffed himself to the gates of Buckingham Palace for two hours.

This came two months after the group's biggest security breach, when Jason Hatch, dressed as Batman, stood for five hours on a ledge of Buckingham Palace after scaling the walls.

Fathers 4 Justice also prompted a security review at Westminster in May when purple flour bombs were thrown at the prime minister, Tony Blair.