Trump launched his “Board of Peace” at the World Economic Forum in Davos in January and some 19 countries have signed its founding charter.

But Italy’s constitution bars the country from joining an organisation led by a single foreign leader.

Prime Minister Giorgia Meloni, a Trump ally, last month noted “constitutional problems” with joining but suggested Trump could perhaps reopen the framework “to meet the needs not only of Italy but also of other European countries”.

Tajani appeared Saturday to rule that out.

“We cannot participate in the Board of Peace because there is a constitutional limit,” he told the ANSA news agency.

“This is insurmountable from a legal standpoint,” he said, the day after meeting US secretary of state Marco Rubio and US Vice President JD Vance at the Olympics in Milan.

Although originally meant to oversee Gaza’s rebuilding, the board’s charter does not limit its role to the Palestinian territory and appears to want to rival the UN.

Key US allies, including France and Britain, have expressed doubts about joining.