French President Francois Hollande urged Luxembourg on Friday to "go as far as possible" in tackling tax avoidance in the wake of the Luxleaks scandal.
Investigative journalists last year found top international companies including Disney, Microsoft and Heinz benefiting from sweetheart tax deals with Luxembourg.
"Luxembourg has committed to bringing in new practices," Hollande said after talks with the tiny duchy's Prime Minister Xavier Bettel in Luxembourg.
But while Hollande praised Luxembourg's "efforts", especially in terms of information sharing, he also "invited Luxembourg to go as far as possible with this harmonisation."
Bettel rejected criticism of his country, saying Luxembourg "will not block anything" when it came to tax but urging new rules for all 28 EU nations.
The "LuxLeaks" scandal exposed deals that saved companies including Apple, IKEA and Pepsi billions of dollars in taxes while Jean-Claude Juncker -- the new president of the European Commission -- was Luxembourg's prime minister.
The scandal erupted when documents from auditing firm PriceWaterhouseCoopers were leaked to investigative journalists last year. Two suspects have been charged over the leaks.
The European Commission, the EU's executive arm, is already carrying out probes into several specific tax deals, including arrangements linking Luxembourg and online retailer Amazon, and Starbucks with the Netherlands.