BEIJING/TAIPEI (Reuters) - China urged the United States on Friday not to allow Taiwan’s president to travel through U.S. territory en route to the island’s diplomatic allies in the Pacific, a sensitive visit shortly ahead of U.S. President Donald Trump’s trip to Beijing.

Taiwan's President Tsai Ing-wen attends a joint news conference with her Honduran counterpart Juan Orlando Hernandez (not pictured) after a private meeting at the Presidential House in Tegucigalpa, Honduras January 9, 2017. REUTERS/Jorge Cabrera

China considers democratic Taiwan to be a wayward province ineligible for state-to-state relations and has never renounced the use of force to bring the island under its control.

China regularly calls Taiwan the most sensitive and important issue between it and the United States, and Beijing always complains to Washington about transit stops by Taiwanese presidents.

President Tsai Ing-wen leaves on Saturday on a weeklong trip to three Pacific island allies - Tuvalu, the Solomon Islands and the Marshall Islands - via Honolulu and Guam.

In a statement on Friday, a Taiwanese government spokesman said Tsai’s trip was aimed at strengthening ties with friendly nations and also to provide support for the island’s frontline diplomats. It said Taiwan was grateful to the United States for helping to arrange the stopovers “in accordance with comfort, safety, convenience and dignity principles.”

Grace Choi, the State Department spokeswoman for East Asian and Pacific Affairs, said Tsai would transit Hawaii Oct. 27-29 and Guam Nov. 3-4.

Choi said Tsai’s transits would be “private and unofficial” and were based on long-standing U.S. practice consistent with “our unofficial relations with Taiwan.” She noted the transits were out of consideration for the safety and convenience of the traveler and there was “no change to the U.S. one-China policy.”

Ambassador James Moriarty, chairman of the American Institute in Taiwan, the organization that carries out unofficial U.S. relations with Taiwan, will greet Tsai in Hawaii and Guam, Choi said.

TRUMP VISIT LOOMS

Trump is due to visit China in less than two weeks. He angered Beijing last December by taking a telephone call from Tsai shortly after he won the presidential election.

China has made “stern representations” to the United States over the matter, said Foreign Ministry spokesman Geng Shuang, urging the United States to strictly abide by the “one China” policy.

China hopes the United States does not allow Tsai “to transit, not send any wrong signals to Taiwan independence forces and take real actions to protect the overall picture of China-U.S. relations and peace and stability in the Taiwan Strait”, Geng told a news briefing.

The trip to the United States will be Tsai's second this year. In January she stopped over in Houston and San Francisco on her way to and from Latin America, visiting the headquarters of micro-messaging service Twitter Inc TWTR.N, which is blocked in China, while in California.

In Houston, she met Republican U.S. Senator Ted Cruz and Texas Governor Greg Abbott. She also spoke by telephone with U.S. Senator John McCain, head of the powerful Senate Committee on Armed Services.

China suspects Tsai wants to push for the formal independence of Taiwan, a red line for Beijing. Tsai says she wants to maintain peace with China but will defend Taiwan’s democracy and security.

China has pressured Taiwan since Tsai took office last year, suspending a regular dialogue mechanism and slowly peeling away its few remaining diplomatic allies.

Just 20 countries now maintain formal ties with Taiwan, instead of China, mostly small states in Central America, the Caribbean and the Pacific.

The United States has no formal ties with Taiwan but is bound by law to help it defend itself and is the island’s main source of arms.

Tsai’s call with Trump was the first between U.S. and Taiwan leaders since President Jimmy Carter switched diplomatic recognition to China from Taiwan in 1979.