Beijing: China on Wednesday expressed displeasure with the ongoing visit of Japanese lawmakers to Taiwan, an island it claims as its territory.

"Certain Japanese politicians, in order to seek selfish political gains, have repeatedly put on political stunts and made provocative visits to China's Taiwan region to bolster and embolden Taiwan independence separatist forces. China firmly opposes this and has made serious demarches to the Japanese side," Chinese Foreign Ministry spokesperson Wang Wenbin said during a press briefing, as quoted by the Chinese Foreign Ministry website.

On Wednesday, Taiwan's foreign office said that a delegation of the Japanese parliament's upper house, headed by ruling Liberal Democratic Party leader Seko Hiroshige, met with Taiwanese leader Tsai Ing-wen and top diplomat Joseph Wu to discuss Indo-Pacific stability and shared regional challenges.

"Hiroshige Seko, Secretary-General of the Liberal Democratic Party of the House of Councillors, and members of the House of Councillors, welcome to Taiwan. Thank you for your continued strong support for Taiwan in the fields of economics and trade. Taiwan is determined to strengthen its defence capabilities. Let us strengthen our cooperation toward the realization of a free and open Indo-Pacific," Taiwan's President tweeted.

Tensions between China and Taiwan, which has been governed independently from the mainland for decades, escalated after US House Speaker Nancy Pelosi visited the island in August. Beijing has warned Western powers against departing from the one-China policy.

Earlier this month, China said that hyping up the threat posed by Beijing to back its military build-up "is doomed to fail." This statement came after Japan unveiled a new national security plan that signals the country's biggest military buildup since World War II.

"Hyping up the China threat to find an excuse for its military build-up is doomed to fail," Wenbin had said during a press conference on December 16.

"Japan's new defence policy ignores facts, deviates from its commitment to China-Japan relations and the common understandings between the two countries, and groundlessly discredits China's defence building and normal military activities. China resolutely opposes this and has made serious demarches to the Japanese side through diplomatic channels," he added.