Thousands of Australians living in the US could find it tougher to extend their stay in America after the Trump administration suddenly issued new visa rules on the weekend.

Expat groups in the US have convened emergency sessions with immigration lawyers after hearing from Australians who have already been denied visa extensions under the tightened rules.

"Right now, we are in full-on — I hate to use the word, but — panic mode for a lot of individuals," American immigration lawyer Jonathan Grode told the ABC.

The changes mean Australians on working visas in the US may have to travel back to Australia every two years to attend an interview at a US consulate.

Until now, Australians commonly travelled much shorter distances to renew their visas at countries like the UK or Barbados.

But a

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