India and China on Saturday traded fresh accusation of border violations in the disputed Himalayan region where their troops this week engaged in the deadliest clash between the two nations in half a century. A day after Indian Prime Minister Narendra Modi asserted that there was no Chinese presence in Indian-held territory in the Ladakh region, his government accused China of seeking to erect structures "just across the Line of Actual Control" that demarcates their respective areas, and refusing India's request to stop. India will not allow any unilateral changes to the disputed border, it said. Mr Modi on Friday called a virtual meeting of all political parties to discuss the clashes on Monday in which at least 20 Indian soldiers were killed and more than 70 injured. China has not disclosed any casualties among its troops. Chinese foreign ministry spokesman Zhao Lijian accused Indian troops of "deliberate provocation" in the area. In a series of tweets, Mr Zhao said the Galwan Valley was on the Chinese side of the line and that India had unilaterally built roads, bridges and other facilities in the region since April. The Indian troops "crossed the Line of Actual Control" and attacked Chinese officers and soldiers who were there for negotiation, triggering "fierce physical conflicts", Mr Zhao said. Mr Modi had appeared to downplay the clash during Friday's meeting, saying, "Nobody has intruded into our border, neither is anybody there now, nor have our posts been captured." His statement raised questions over whether the clashes took place in Indian or Chinese-held territory and contradicted statements by the Indian foreign ministry. Hour later Just two days earlier, Foreign Minister Subrahmanyam Jaishankar told his Chinese counterpart Wang Yi that the Chinese army had tried to erect a post in the Galwan Valley on the Indian side of the Line of Actual Control – which extends from west to east for almost 3,500 kilometres. In a statement after the call, New Delhi accused China of an “intent to change the facts on ground in violation of all our agreements to not change the status quo”. The clashes broke out despite repeated assurance from both sides that a weeks-long standoff in the area was being resolved through diplomatic and military talks. Both sides gave competing versions of the violence. Beijing claimed Indian troops "crossed the border line twice... provoking and attacking Chinese personnel, resulting in serious physical confrontation between border forces on the two sides". But Indian foreign ministry spokesman Anurag Srivastava said the clash arose from "an attempt by the Chinese side to unilaterally change the status quo" on the border. The clashes reportedly involved intense fighting and no gunfire, in line with longstanding tactics to avoid a full-scale military battle. The soldiers threw punches and stones at each other, with Chinese troops allegedly attacking their Indian counterparts with rods and nail-studded clubs during the more than six-hour fight, Indian media reported. The recent uptick in tensions began in early May, when several Indian and Chinese soldiers were injured in a clash involving fists and stone-throwing.