China criticized India on Thursday for trespassing onto Chinese territory under the cloak of "protecting Bhutan", and questioned India's so-called security concerns regarding the construction of a road by China.

Foreign Ministry spokesman Geng Shuang told reporters at a daily news conference in Beijing that China is willing to peacefully solve the issue through diplomatic channels, but a precondition is the unconditional withdrawal of Indian troops.

It has been 21 days since Indian border troops crossed into the Sikkim section of the China-India border, a demarcation that has been recognized by both countries for decades.

"The trespassing of Indian border troops took place at the defined Sikkim section of the China-India boundary, which is different in nature from the previous standoffs between the two sides at the undefined sections of the border," Geng said. "The Indian side crossed into Chinese territory and changed the status quo. Only when India pulls back its troops, will the status quo be restored."

The Doklam area has always been part of China's territory and under its effective jurisdiction. China and Bhutan have held 24 rounds of boundary negotiations since they launched the talks in the 1980s. There is no disagreement between the two sides on the fact that Doklam belongs to China, though the boundary is not yet officially demarcated.

"The fact is that the Indian side 'justified' its incursion under the cloak of 'protecting Bhutan', and attempted to create a dispute in Doklam to prevent and contain border negotiations between China and Bhutan," Geng said.

He said he also doubts India's so-called security concerns regarding China's road construction, saying "it is justifiable and reasonable behavior of a sovereign state to build roads on its own territory".

"It is the Indian side that has built facilities on the Sikkim section of the China-India boundary, conducted mass troop deployment and even built military facilities on and across the border, changing the status quo in the border area," Geng said.

"We again urge India to immediately pull back its troops to the Indian side to avoid a more serious situation and consequences," Geng added.