China on Tuesday again told India to withdraw its troops from the disputed border at Doklam as a Chinese newspaper warned that Beijing was battle ready and not afraid to go to war with India in an "all-out confrontation".

Foreign Ministry spokesperson Lu Kang said foreign diplomats in Beijing were briefed over the Doklam stand-off and that Indian troops had "illegally" crossed the mutually recognised China-India boundary on the Sikkim section. 

He said India "should not take the illegal trespass as a policy to realise its political target" adding, the foreign diplomats in Beijing were "shocked" over the trespass by India.

China and India have a 3,488-km border, of which 220 km falls in the Sikkim sector where Doklam is situated. Doklam is at a tri-junction between India, China and Bhutan. 

China calls Doklam its own, a claim contested by India and Bhutan.

China said India violated international rules by "illegally entering into the Chinese territory". Beijing has been trying to rally international support behind it.

"The illegal trespass by the Indian border personnel has drawn extensive attention from the international community and many foreign diplomatic missions in China said they were shocked by this," Lu said.

"We stressed the facts are very clear in this incident. The Sikim section on China-India boundary is mutually recognised by the two sides," Lu added. "This time the Indian border personnel illegally trespassed into Chinese territory."

Lu warned India to withdraw troops from Doklam to avoid an escalation. "We hope the Indian side get the clear understanding of the current situation and take immediate measures to pull back the personnel."

Meanwhile, a commentary in the state-run Global Times said China doesn't fear going to war and will make itself ready for a long-term confrontation.

The article by Duo Mu said China must deploy more troops along the border with India and speed up road construction in Doklam where the two sides have been engaged in a month-long standoff.

It suggested that New Delhi triggered the dispute as it was worried over China's rapid economic rise. The stand-off began when Indian troops stopped Chinese soldiers from building a road in Doklam.

"China doesn't fear going to war to safeguard sovereignty either, and will make itself ready for a long-term confrontation," said the commentary.

The writer said one important reason that prompted India to trigger the border dispute was its worry over China's economic development. 

"China has risen quickly to be the world's No. 2 economy… New Delhi is deeply concerned with China's rapid rise. Provocation at the border reflects India's worry and attempt to sound out China."

The commentary said China doesn't recognise the land under India's actual control as Indian territory and accused New Delhi of "poisoning" the atmosphere for border negotiations.

"China must be prepared for future conflicts and confrontation. China can take further counter-measures along the Line of Actual Control (LAC).

"If India stirs up conflicts in several spots, it must face the consequence of an all-out confrontation with China along the entire LAC. The 3,500-km border has never been short of disputes. Since the 1962 border war, the Indian side has repeatedly made provocations."

China must continue strengthening border construction and speed up troop deployment and construction in the Doklam area, Duo said. "These are legitimate actions of a sovereign country."