Zimbabwean President Robert Mugabe and his wife Grace attended the 21st Movement Celebrations to mark his 93rd birthday celebrations at Matopos National Park in Mateleland South, Zimbabwe, Feb. 25, 2017. (Xinhua/Stringer)

HARARE, Feb. 25 (Xinhua) -- Zimbabwean President Robert Mugabe on Saturday marked his 93rd birthday with a lavish party organized by the youth wing in his Zanu-PF party in Matopos, Matabeleland South.

The veteran, who is the world's oldest leader, turned 93 on February 21 and every year youths in his party organize a massive birthday celebration in his honor under the banner of the 21st February Movement.

Thousands of Zanu-PF supporters attended the ceremony, held just outside the country's second largest city of Bulawayo.

In his wide-ranging speech, the president thanked God for the long life, saying 93 years was a "long, long journey filled with both joy and sorrow."

Left with one sibling, the president said there were times when he felt lonely after having lost many of his siblings, but reckoned that perhaps he could have been given a long running mandate by God.

"When I look back, I say, aah, Oh Lord, why have these (siblings) been taken before me and why have I remained so long alone and alive?" the president said.

Turning to politics, the president spoke on divisions in his party over succession and reiterated that people should not canvass for positions but should let the people choose them.

"The party is based on a party constitution and the party constitution provides how people get elected from one position to another. So why want to try to circumvent the constitution?" the president said.

His party has in recent years been rocked by intense infighting by factions vying to succeed him, one reportedly led by Vice President Emmerson Mnangagwa and another by a younger generation of leaders going by the name G40.

Both factions deny the accusations.

Mugabe warned the "ambitious" leaders that they would never succeed in toppling him.

He recently said he was not ready to step down and would not groom a successor as that was the responsibility of the people.

Zanu-PF has endorsed him as the party's presidential candidate for the 2018 elections when he will be 94.

He said even as some people within his party continue to call for his resignation, he would only step down when his party says so.

The veteran president said he would also not impose a party leader, as that would be in violation of the party constitution.

"I don't want to choose a leader for the party. I only choose my two vice presidents (Mnangagwa and Phelekezela Mphoko) and the issue about my successor that is a constitutional issue, an issue of the party congress," he said.

He told party members to wait for the 2019 Zanu-PF elective congress to deal with the succession issue, and indicated that his successor must be a person of impeccable credentials and a principled leader who would not reverse some of the gains of the country's liberation struggle including the land reform program.

His wife Grace Mugabe also addressed the gathering and said her husband's 93rd birthday was a milestone achievement.

She hailed Mugabe as a loving husband, exemplary father, statesman and iconic and great leader of Africa.

"He is everything virtuous to the downtrodden of this world," the First Lady said.

Earlier, Mugabe let 93 balloons into the air to mark the start of the celebrations at Matopos.