* Pelosi to tour Singapore, Malaysia, South Korea and Japan
* No mention of Taiwan on her agenda
* Chinese Air Force reiterates will to defend territory
* Chinese military drills in South China Sea (Updates with expected arrival in Singapore)
By Yew Lun Tian
BEIJING, July 31 (Reuters) - U.S. House of Representatives Speaker Nancy Pelosi starts a tour of four Asian countries on Sunday, her office said, without mentioning Taiwan amid intense speculation she might visit the self-ruled island claimed by China.
"Speaker Nancy Pelosi is leading a Congressional delegation to the Indo-Pacific region, including visits to Singapore, Malaysia, South Korea and Japan," her office said in a statement https://www.speaker.gov/newsroom/73122.
It said the visit would include those countries, but did not specify whether Pelosi, who is number 3 in the line of presidential succession, might make other stops.
"The trip will focus on mutual security, economic partnership and democratic governance in the Indo-Pacific region," it said.
Gregory Meeks, chair of the House Foreign Affairs Committee, was among the delegation.
Pelosi was expected to arrive in Singapore on Monday for a two-day visit, broadcaster CNA reported, citing the country's foreign ministry. The American Chamber of Commerce in Singapore was scheduled to host a reception with her on Monday afternoon, its website site.
China views visits by U.S. officials to Taiwan as sending an encouraging signal to the pro-independence camp in the island. Washington does not have official diplomatic ties with Taiwan but is bound by law to provide the island with the means to defend itself.
A visit by Pelosi would be a dramatic, though not unprecedented, show of U.S. support for Taiwan. Republican Newt Gingrich was the last House speaker to visit Taiwan in 1997.
President Xi Jinping warned his U.S. counterpart Joe Biden on Thursday that Washington should abide by the one-China principle and "those who play with fire will perish by it".
Biden told Xi that U.S. policy on Taiwan had not changed and that Washington strongly opposes unilateral efforts to change the status quo or undermine peace and stability across the Taiwan Strait.
Taiwan's foreign ministry said on Friday after the call between Xi and Biden that Taiwan would continue to deepen its close security partnership with the United States.
Chinese air force spokesman Shen Jinke was quoted by state media as saying on Sunday that Beijing would "resolutely safeguard national sovereignty and territorial integrity".