LONDON -- A portrait of Queen Elizabeth II was defaced with spray paint Thursday at London's Westminster Abbey, and police arrested a man at the church on suspicion of vandalism.

Fathers 4 Justice, a protest group that campaigns on behalf of fathers denied contact with their children, said the arrested man was a member. It said he had written "Help" with paint on the picture in the abbey's Chapter House.

"It was basically a dad that was desperate to see his kids in the run-up to Father's Day," Fathers 4 Justice campaign director Jolly Stanesby said. "He's decided to ask for help."

Stanesby said the action wasn't an official protest organized by the group.

Police said a 41-year-old man was arrested on suspicion of criminal damage and taken to a London police station.

The abbey said the painting by Australia-born artist Ralph Heimans has been removed from public view until it can be restored.

The portrait was commissioned to mark last year's anniversary of the queen's 60 years on the throne. It was on display until March in Australia's National Portrait Gallery in Canberra and was recently bought by Westminster Abbey for its collection.

The 9-foot by 11-foot painting shows the monarch standing on the spot in the abbey where she was crowned.

Last week, the queen and her family attended a ceremony in the abbey to mark the 60th anniversary of her coronation there in June 1953.

Buckingham Palace declined to comment on the vandalism incident.

Fathers 4 Justice emerged about a decade ago and made headlines with high-profile demonstrations, including having members dressed as superheroes scale Buckingham Palace and Westminster Abbey.

In 2004, members caused panic in the House of Commons chamber when they hurled purple powder at then-Prime Minister Tony Blair from the public gallery.

The original group splintered in 2006 following allegations that extremist members were plotting to kidnap Blair's young son Leo.

Stanesby -- who was once fined for climbing the Stonehenge monument dressed as cartoon character Fred Flintstone -- said the group had spent several years trying to lobby politicians for changes in the law. He said it had been ignored by politicians and would now revert to "nonviolent direct action."