GLOBAL unions united in protest today as they developed plans to take on multinational companies Tenaris and Ternium as their billionaire boss was charged with bribery.

Paolo Rocca is being investigated for his involvement over allegations of payments made to an Argentinian government official through the company in 2008.

Tenaris, a leading supplier of tubes to the energy industry, gave "its full support for its chairman and CEO” soon after the news broke.

It said in a statement that it was “monitoring the situation together with its lawyers” as the company shares plummeted by 8 per cent.

Unions from Argentina, Brazil, Canada, Colombia, Guatemala, Indonesia, Italy, Mexico, Romania and USA gathered in Mexico City as the Tenaris-Ternium Workers’ World Council developed a strategy to tackle the attacks on trade unionists committed at the companies various international operations.

Industriall warned the companies, both owned by Techint, “are violating workers’ rights, provoking wage disputes and threatening to relocate plants to lower wage countries despite earning over US$1.5 billion in profits in 2017.”

Techint is implicated in the massive Lava Jato corruption scandal in Brazil and has a history of avoiding taxes by moving its headquarters and establishing offshore companies.

Sintratucar President Walberto Marrugo explained that Tenaris has “terrorised” union leaders in Colombia and illegally filmed union activities, putting member lives at risk in the world’s most dangerous country for trade unionists.

Delegates heard that steel giant Ternium sacked leading members of the Sitraternium union in Guatemala and refuses to negotiate with them, leading to a referral to the International Labour Organisation.

Industriall spokesman Adam Lee warned: “Companies that abuse workers are often irresponsible across the board and Tenaris and Ternium are no exception.”

“The Tenaris-Ternium Workers’ World Council demands that the companies change course and enter into social dialogue with unions globally.”