The 52-year-old former frontman of The Smiths also announced to the crowd in Buenos Aires on Sunday that “We all know that the Malvinas [Falklands] are Argentina’s.”
The provocative T-shirts featured a photo of the royal couple on their wedding day, with the ‘We hate William and Kate’ slogan surrounding the shot in block capital letters.
Morrissey also told the crowd from the stage: “The [British] government, the governments, never listen to the people, to their pain.”
The singer-whinger asked his fans not to “blame” the British people over the Falklands “because it is the government that decides”.
Tensions have been high in Argentina since Prince William was posted to the Falklands for a six-week RAF flight training operation last month.
The 30th anniversary of the start of the Falklands War is on April 2.
Morrissey is the latest in a long line of celebrities who fancy themselves international diplomats to have spoken out on the Falklands issue.
Sean Penn caused controversy by accusing Britain of “archaic” colonialism during a meeting in Buenos Aires.
And Pink Floyd’s Roger Waters told Chilean TV last week that the Falklands “should be Argentine”.
The British government has said that the islands will remain a British territory as long as a majority of the 3000 islanders want them to be.
Pictures: Morrissey performing in Chile’s 53nd Vina del Mar International Song Festival, 24th Feb 2012 (Getty images)