(Reuters) - China has pulled its badminton players out of this week's Japan Open amid a worsening political crisis over disputed islands, leaving organisers to hastily re-draw for the event.

An official at the Tokyo championships, speaking on condition of anonymity, said none of the Chinese players expected for the tournament had appeared.

"They were entered but won't be taking part," he said.

The official added he had not heard any specific reason for this but "some sort of political reason could be suspected."

However, Li Yongbo, general coach of China's badminton team, was reported as saying the cancellation was due to the team's tiredness after the Olympics, the Badminton Super League and the Masters Super Series in a row.

Li could not be reached by a Reuters reporter.

An employee of the Table Tennis & Badminton Management Center at General Administration of Sport of China said the decision to miss the tournament in Japan had been made in the past two days, but she would not say why.

A long-standing dispute over an uninhabited group of islands in the East China Sea -- known as the Senkaku in Japan and Diaoyu in China -- took a fresh twist across China on Tuesday after two Japanese activists landed on one of the islands.

Beijing described the landing as provocative, lodged a complaint with Tokyo and said it reserved the right to "take further action".

The spat escalated on the anniversary of Japan's pre-war invasion of its giant neighbour, with relations between Asia's two biggest economies faltering badly.

The dispute led to a day of anti-Japan protests in China. Japanese businesses shut hundreds of stores and plants across China and Japan's embassy in Beijing again came under siege by protesters hurling water bottles, waving Chinese flags, and chanting anti-Japan slogans, evoking war-time enmity.

The Japanese government last week decided to nationalise some of the islands, buying them from a private Japanese owner, in a move which inflamed the dispute.

Political analysts say China also upped the stakes last week when it announced precise boundaries for waters it claims around the islands.

China's badminton elite would appear to be another casualty of the diplomatic row.

Brief profiles of the leading Chinese players still appeared on the tournament's website on Tuesday in a section highlighting favourites for victory.

Their absence opens the door for Malaysia's world number two Lee Chong Wei to reclaim the title, having suffered a shock defeat to China's Chen Long in last year's title match.

"It's unfortunate that China have withdrawn as it will certainly dilute the level of competition," Malaysia's singles coach Rashid Sidek said. "Chong Wei is our trump card."

With the Chinese out of the men's draw, Lee Chong Wei is seeded first seed, Denmark's Peter Gade second, Simon Santoso of Indonesia third and Japan's Sho Sasaki seeded fourth.

• Please wait.

• Golf: Johnson triumphs by one stroke at Mobile Bay LPGA
• Results worldwide
• Bradley clings to lead in Texas with surging Korean one stroke adrift
• Classy Williams sweeps Azarenka aside in final
• Kien Keat-Boon Heong may not play in Group C tie against Germany
• Kjaersfeldt ready to continue strong Danish tradition
• Broad salutes Anderson as England hammer Kiwis
• Aussie Griffin an easy winner at fog-bound Korean Open
• Sarawakian Daniel makes a winning return from injury
• Tensions put aside as North Korea beat South for gold