BEIJING — A century after his birth and nearly 15 years after his death, Zhao Ziyang, the reformist Chinese Communist Party leader who opposed the armed suppression of student protests in 1989, was given a quiet burial in Beijing on Friday under police guard.

The low-key, long-delayed ceremony was the latest episode showing that even in death, Mr. Zhao remains a sensitive topic in Chinese politics.

His ashes were interred in a cemetery on the northern outskirts of Beijing during a small ceremony for close family members, ending a quarrel with the party authorities over where to place his remains. He was buried alongside the ashes of his wife, Liang Boqi, who died in 2013.

“After many years of delays, the children of Zhao Ziyang have finally been able to put to rest their long-deceased father and mother,” his children said in a statement shared by Bao Pu, a Hong Kong publisher who issued Mr. Zhao’s posthumous memoirs.