Tennis player Li Na of China attends a news conference for the Pan Pacific Open tennis tournament in Tokyo September 23, 2012. Li stuck to the business of tennis before her appearance in this week's Pan Pacific Open in Japan, refusing to comment on a deepening political crisis between the two countries over disputed islands. [Photo/Agencies]

TOKYO - China's Li Na stuck to the business of tennis before her appearance in this week's Pan Pacific Open in Japan, refusing to comment on a deepening political crisis between the two countries over disputed islands.

Li sat stony-faced at a press gathering on Sunday as an official from the women's WTA tour said repeatedly last year's French Open champion would not answer questions on the row.  

"After the US Open I got a little bit sick," said Li, still struggling with a cough, before the questions turned to a more political nature.

"My book was out so I was busy for three days signing autographs."

Any inquiry about the diplomatic flare-up between China and Japan was immediately shot down by WTA officials.

China had withdrawn its badminton players from last week's Japan Open as tempers flared over a group of uninhabited islands in the East China Sea.

Japan pulled out of the second leg of the Asian Sevens Series in Shanghai.

The Japanese government's decision to nationalise some of the islands -- known as the Senkaku in Japan and Diaoyu in China -- triggered angry protests across China.

The political row escalated on the anniversary of Japan's pre-war invasion of its Asian neighbour, with relations between Asia's two biggest economies deteriorating rapidly.

Li, who has had her share of run-ins with Chinese authorities, kept silent when asked if she had come under pressure for taking part in Tokyo.

The 30-year-old insisted she will be fighting fit at the $2.16 million Tokyo tournament, and credited new coach Carlos Rodriguez for her more positive attitude.

"I want to stand up again," said Li. "My ex-coach (husband Jiang Shan) didn't do a good job. It's very tough to be a coach and a husband. It's very tough to find the right balance.

"My goal is the end of year (Championships in Istanbul)," she added. "I've reached number eight so I'm pretty close (to locking up her spot).

"There's not much time left so I have to work even harder."