The Duke of Cambridge will be wearing the uniform of a "conqueror" when he deploys to the Falklands later this year, Argentina has said.
The barb came with tensions running high over the disputed islands, which Buenos Aires calls Las Malvinas.
On Tuesday it emerged that one of the Royal Navy's most advanced new warships is being sent to the area.
However, the Ministry of Defence stressed that the mission was routine.
David Cameron and Argentine president Cristina Fernandez have previously accused each other of "colonial" behaviour.
Referring to the deployment of HMS Dauntless and William's tour of duty as an RAF search and rescue pilot, Argentina's Foreign Ministry said it "rejected the British attempt to militarise [the] conflict".
It also expressed regret that an heir to the throne would arrive wearing "the uniform of a conqueror".
"Governments should avoid the temptation of falling into a discourse... that aims to distract public attention from belt-tightening economic policies," the ministry said in a statement.
It has also emerged that UK foreign minister Jeremy Browne will be visiting the islands in June to coincide with the 30th anniversary of the war.