MADRID — A Spanish artist painted a dove on the tomb of Gen. Francisco Franco on Wednesday as a protest against the former dictator, the latest in a series of controversies over his tomb and plans to move his remains.

The artist, Enrique Tenreiro, smuggled red paint through the security gate of the huge underground basilica that Franco had built, spray-painting the words “For Freedom” along with the dove on the tomb.

Mr. Tenreiro, who was taken away by a guard and faces a police investigation, issued a statement saying that he had not meant to offend Franco’s family and supporters, but had wanted to “alleviate the suffering of those who lost a Civil War that shouldn’t have occurred.”

What does the government plan to do with Franco’s remains?

The protest came amid a heated debate set off by Prime Minister Pedro Sánchez’s decision to exhume Franco’s remains from the basilica, built on a site known as the Valley of the Fallen, an hour’s drive from Madrid.