A US judge has blocked Trump's $100,000 charge for skilled visa applicants.

On Monday, a US district judge banned President Donald Trump's plan to impose a $100,000 fee on firms who file visa applications for foreign highly qualified workers.

In a case filed by 20 Democratic-controlled states, District Judge Leo Sorokin concluded that the move exceeded Congress' taxing authority, and that the price for H-1B visas was an illegal tax.

"The substance and application of the $100,000 payment reveal that it is a tax, regardless of what the payment is called," Sorokin concluded in his 42-page decision.

"The President had no power or delegated authority to impose a tax on H-1B petitions," he stated.

In December, a different federal judge upheld the $100,000 fee in a separate case. The verdict is currently being appealed.