Sean Penn has criticised the "unthinkable" decision to send Prince William to the Falklands - a day after the actor slammed the UK's "colonialist" presence there.
The second-in-line to the throne is on a six-week RAF mission to the islands, and the UK's most powerful destroyer, the HMS Dauntless, has also been sent there.
Britain has denied it is turning the dispute with Argentina into a military row, and said the Duke of Cambridge is simply serving as a search-and-rescue helicopter pilot .
But Hollywood star Penn, who is UN ambassador at large for Haiti , has called it a provocation.
He said: "It's unthinkable that the United Kingdom can make a conscious decision to deploy a prince within the military to the Malvinas, knowing the great emotional sensitivity both of mothers and fathers in the United Kingdom and in Argentina who lost sons and daughters in a war over islands with a population of so few.
"There are many places to deploy a prince. It's not necessary when the deployment of a prince is generally accompanied by a warship, to send them into seas of such spilled blood."
The actor was speaking after meeting President Jose Mujica of Uruguay, which contributes to the UN peacekeeping force in Haiti.
Earlier this week, Penn seemed to express support for Argentina's push for a UN-sponsored negotiated settlement to the dispute.
He urged Britain to join proposed UN-sponsored talks over what he called "the Malvinas Islands of Argentina" and went on to criticise the UK, saying: "The world today is not going to tolerate any ludicrous and archaic commitment to colonialist ideology."
But he has now said British journalists twisted his comments and accused the media of pushing for war instead of diplomacy to resolve the row over the islands both countries claim in the South Atlantic.
Condemning criticism of his earlier comments, he said: "My oh my, aren't people sensitive to the word 'colonialism,' particularly those who implement colonialism."
The Falklands took the case to the UN , where foreign minister Hector Timerman criticised the UK, saying the islands represent "the last refuge of a declining empire".
Britain has refused to negotiate as long as Falklanders want to remain part of the British realm - and is increasing its military defences ahead of the 30th anniversary of Argentina's failed effort to seize the islands.