The body of Liu Xiaobo, the Nobel laureate who died after years of imprisonment in China, was cremated Saturday after a private ceremony attended by his family and several men believed to be Chinese secret police.

Liu's remains were incinerated "in accordance with the will of his family members and local customs" in the northeastern city of Shenyang, said Zhang Qingyang, an official from the municipal office.

His ashes were later scattered in the sea.

Officials released photos showing his wife, the poet Liu Xia, with her brother, and two of Liu Xiaobo's brothers in front of the body, which was covered with white petals and surrounded by flowers at a funeral home.

Zhang also said "friends" were at the ceremony, but an Amnesty International researcher said he did not recognise any of the row of non-family members in the official photo and people close to the Liu couple identified at least one "state security police officer" among them.