TOKYO (AFP) - Japan's Prime Minister Shinzo Abe donated a tree to the controversial Yasukuni war shrine on Monday, but did not visit the memorial which is seen by China and South Korea as a symbol of Japan's militarist past.

Abe donated the symbolic gift, a sacred "masakaki" tree, to coincide with the start of a three-day spring festival, Jiji Press news agency and other local media said.

The offering was seen as a sign that he would avoid a personal visit during the festival, reports said, with public broadcaster NHK quoting anonymous sources as saying he was not planning a trip.

Abe had been widely expected to refrain from visiting the shrine ahead of US President Barack Obama's visit to Tokyo from Wednesday to Friday, with Washington calling for Asian neighbours to mend ties.

Many other lawmakers are however expected to make their regular pilgrimage on Tuesday.

The 145-year-old Shinto shrine honours Japan's war dead including several leaders condemned as "Class A" war criminals by the US-led allied powers and executed after World War II.

Abe, known for his nationalist views, drew protests from China and South Korea when he visited the shrine last December at a time when Japan's ties with the neighbouring countries were severely strained over territorial disputes and differences in historical perceptions.

Conservative Japanese parliamentarians make pilgrimages to the shrine during spring and autumn festivals and on the war anniversary.

Abe made the same kind of tree offering at the autumn festival last year, but did not visit the shrine.

Yasukuni is a flashpoint in relations between Japan and its Asian neighbours, with disagreements about history badly colouring relations.

Beijing and Seoul see Yasukuni as a painful reminder of Japan's imperialist past because it enshrines some of the men who ran the country and its military during years of brutal expansionism.

But Japanese conservatives say it is natural that they pay homage to people who lost their lives in the service of their country.

Keiji Furuya, chairman of the National Public Safety Commission, visited the shrine on Sunday, becoming the second minister in Abe's Cabinet to go there in the past week.

"I made the visit today so that it would not interrupt my official duty," Furuya said in a statement to Japanese media.