The Japanese family that owns a chain of East China Sea islands at the centre of a territorial row between Tokyo and Beijing said Friday it wants to sell the tiny archipelago "as soon as we can".

The Kurihara family, which owns the islands known as Senkaku in Japanese and Diaoyu in Chinese, leases the chain to the Japanese government.

The family has been negotiating with Tokyo city officials over a sale -- valued up to 1.5 billion yen ($19 million) according to reports -- as the current lease agreement gets set to expire in March next year.

"We have the term for a lease contract with the state government until the end of March next year, so we would like to seal the deal (with Tokyo) shortly after that," said Hiroyuki Kurihara, one of the family's younger brothers.

"We would like to conclude the talks as early as we can," he told the Foreign Correspondents' Club of Japan.

His comments come less than a week after Japan's ambassador to China returned to Beijing, after being summoned to Tokyo for crisis talks over the disputed islands.

Tensions between the two countries rose last week after Chinese vessels twice entered waters near the resource-rich islands, which are claimed by Beijing and Tokyo.

Japan lodged two formal complaints with Beijing last week and summoned the Chinese ambassador to Japan in protest.

The uninhabited outcrops were the scene of a particularly nasty spat in late 2010 when Japan arrested a Chinese trawlerman who had rammed two of its coastguard vessels.

Tensions spiked in April after controversial Tokyo governor Shintaro Ishihara, an outspoken critic of Beijing who has made a career out of provocative nationalistic remarks, called for Tokyo to buy the islands.

Earlier this month, Japanese Prime Minister Yoshihiko Noda said the central government was also considering buying the island chain of islands, sparking an angry response from Beijing.

However Kurihara on Friday ruled out a sale to the national government unless it reaches a separate deal with Tokyo, which has raised as much as 1.37 billion yen in public donations to finance a purchase.

A sale would mark a new stage in the long-rumbling dispute over the islands, which sit around 2,000 kilometres (1,250 miles) from Tokyo in rich fishing grounds that may harbour lucrative energy resources.

The Kurihara family bought the islands decades ago from descendants of the previous Japanese owners on a condition that they will not sell them off to private entities.

The islands were inhabited by Japanese fishermen before the end of World War II.