The Pope will not participate in US President Donald Trump’s Board of Peace, the Vatican’s top diplomat has confirmed.

Pope Leo was invited to join the board in January but declined citing a number of perplexing issues, reported Vatican News, the official outlet for the pontiff.

The Vatican’s top diplomat Pietro Parolin made the comments to journalists after a meeting with the Italian Government.

The diplomat said it was important to respond to the invitation and there were “certain critical issues that should be resolved”, reported the Vatican News.

“One concern is that, at the international level, it should above all be the UN that manages these crisis situations,” said Parolin. “This is one of the points on which we have insisted.”

The board started to end the war in Gaza and help with its rebuild, however, its remit has grown over time with Trump saying its work will be “go far beyond Gaza”, reported CNN.

The board’s charter makes no mention of Gaza, according to The Times of Israel, and countries must pay US$1 billion ($1.7b) to join the board permanently.

The charter names Trump as chairman and he controls much of the board’s work. There is no term limit for the chairman.

The executive board is made up of eight members, including the likes of US special envoy to the Middle East Steve Witkoff, former British Prime Minister Tony Blair and World Bank president Ajay Banga, according to Al Jazeera.

To date, board members have pledged US$5b “towards the Gaza humanitarian and reconstruction efforts”, the White House said on social media.

The Pope’s decision comes before the first board meeting on Thursday. White House press secretary Karoline Leavitt told journalists more than 20 countries will attend, with some being observers rather than members.

The White House has invited 50 countries to join the board, said Al Jazeera. Key European powers such as France, Germany, Britain and Spain declined, although many Arab states, like Saudi Arabia, Turkey and Jordan, have joined. New Zealand announced it would not join the board in its current form.

The White House press secretary told reporters the Vatican decision was “deeply unfortunate”.