German Development Minister Svenja Schulze has called for greater international taxation of the super-rich along with counterparts in Spain, Brazil and South Africa.

"There are currently around 3,000 billionaires worldwide. A tax could be set up as a minimum levy of 2% on the assets of the super-rich," Schulze wrote in an opinion piece on Thursday.

Spanish Economy Minister Carlos Cuerpo, Spanish Finance Minister María Jesús Montero, South African Finance Minister Enoch Godongwana and Brazilian Economy Minister Fernando Haddad also put their names to the article, which appeared in Germany's Der Spiegel magazine and several other publications worldwide.

"It would not apply to billionaires who already pay an appropriate amount of income tax. However, all those who manage to avoid income tax would be obliged to contribute more to the common good," the ministers added.

Tax systems must comply with the principle of fairness, they said.

"To achieve this, the contribution of each and every individual must be in line with their ability to pay. However, existing tax privileges mean that the super-rich can minimize their income taxes," the article added.

Globally, billionaires only pay up to 0.5% of their wealth in private income tax.

The ministers described a new tax era as a step towards greater social justice.

"It would also generate much-needed revenue for governments to invest in public services such as health, the environment and infrastructure," they wrote.

"This would benefit everyone, including those at the top of the income pyramid. According to estimates, such a tax could generate an additional $250 billion a year in revenue worldwide."