Hundreds of protestors descended on the Lusaka headquarters of Konkola Copper Mines (KCM) on 30 May amid growing anger that the parent company, London-based Vedanta, is boosting its profits via tax avoidance schemes.

Marchers called for a full audit of the KCM operation in Zambia as protestors say that by reeling in bumper profits, but by paying low taxes, it is depriving the country of revenue.

The protest followed the release of a video in which the chairman of the FTSE 250-listed Vedanta, Anil Agarwal, apparently boasted of the vast profits that the company is making from the KCM mine.

The video shows Agarwal speaking at a business conference in Bangalore in March.

"We took over the company. It's been nine years, and since then, every year it is giving us a minimum of $500m (£299m, €367m) plus $1bn every year... it has been continuously giving back," he said in the video.

The comments seem to be at odds with the company's publicly reported profits. Vedanta's last set of accounts show a $15.9m operating loss from its operations in Zambia, while it reported a $63.6m profit the year before.

The protest was organised by international charity ActionAid, which called for greater transparency over KCM's tax affairs, in a statement on 30 May.

"Zambia's citizens are up in arms. If KCM is engaged in tax avoidance, it would be depriving Zambia of vital revenue through taxes and dividend payments to the government," said ActionAid's Zambia director Pamela Chisanga in a statement.

"Vedanta and KCM must pay their fair share of tax. The Zambian government should carry out a forensic audit of KCM's accounts and publish the results."

Vedanta said the Agarwal video has been interpreted "out of context" while the chairman added that the company had invested nearly $3bn in the country and "taken very little out."

The Zambian Revenue Authority has begun an investigation KCM's tax affairs but ActionAid is calling on the Zambian government to carry out a forensic audit of the company.