Russia congratulated Pope Francis Wednesday on 11 years in office, hailing his support for "humanism and peace" after the pontiff caused outrage by urging Ukraine to "raise the white flag".

"Pope Francis is a true and sincere advocate of humanism, peace and traditional values," the Russian embassy to the Holy See posted on X, formerly Twitter, in English.

It offered the embassy's "best wishes" to the 87-year-old, describing him as "one of the few political leaders with a truly strategic viewpoint on world problems".

Francis marked 11 years since being named head of the Catholic Church on March 13, 2013, amid a diplomatic storm.

In an interview conducted last month and broadcast Saturday, the Argentine urged Kyiv, which has been fighting invading Russian forces for two years, to "raise the white flag and negotiate".

The Ukrainian government reacted with fury, even while the Vatican insisted that the words "white flag" were intended to mean a cessation of hostilities, not a surrender.

At his weekly audience on Wednesday morning at the Vatican, Francis - speaking in general terms - prayed for an end to "this madness of war, which is always a defeat".