Pope Leo warned of the risk of democracies sliding into “majoritarian tyranny” on Tuesday, in a ​letter issued by the Vatican two days after US President Donald Trump attacked the pontiff on social media.

The first US pope, writing to participants of a Vatican meeting about the use of power in democratic ​societies, said democracies remained healthy only when they were ​rooted in moral values.

“Lacking this foundation, (democracy) risks becoming either ⁠a majoritarian tyranny or a mask for the dominance of ​economic and technological elites,” said Leo in the letter.

The text, released ​as the pope was undertaking an ambitious, 10-day tour of four African countries, did not directly address the US or name any specific democracies.

Trump sharply ​criticised Leo as “terrible” on Sunday night, after the pope had emerged in recent weeks as a growing critic of the US-Israeli war on Iran.

Leo told Reuters ‌on ⁠Monday that he planned to keep criticising the war, despite Trump’s comments.

In Tuesday’s letter, the pope said the Catholic Church taught that power could not be seen as an end in ​itself “but as a ​means ordered toward ⁠the common good”.

“This implies that the legitimacy of authority depends not on the accumulation of economic ​or technological strength, but on the wisdom and ​virtue ⁠with which it is exercised,” said Leo.

The pope also urged leaders in democratic societies to avoid any temptation to hoard power.

“Temperance … proves ⁠essential ​for the legitimate use of authority, for ​true temperance restrains inordinate self-exaltation and acts as a guardrail against the abuse ​of power,” he said.