Clarence House has confirmed that three individuals were given placements - which ranged from six weeks to two years - in order to develop their careers.
Suggestions that they were posted to Whitehall in order to influence policy of behalf of the Prince were strongly denied.
However some MPs have raised concerns about the placements, saying they will raise the issue in the Commons when Parliament returns next month.
"Three secondments in the past five years at relatively junior levels does not warrant concern," a Number 10 spokesman told reporters.
"There is nothing unusual about government departments taking on secondees from other bits of the public sector or indeed the private sector.
"None of the work that they undertook when seconded into government was directly related to the Duchy of Cornwall."
The disclosure came after it emerged that the Prince had had 36 private meetings with Cabinet ministers since the general election in 2010.
"It raises constitutional questions about the influence the monarch in waiting has over policy and there will be questions in the House when it returns," he told The Sunday Times.