A team of Afghan girls who had been denied visas to attend a Washington robotics competition are now allowed to come, organizers said Wednesday.

U.S. authorities had originally refused access to schoolchildren from a number of Muslim-majority nations to participate in the science contest, decisions that followed implementation of stricter visa policies under President Donald Trump.

But Trump urged a reversal of course following public outcry over the Afghan girls' inability to attend the event, according to U.S. media.

"I am most grateful to the U.S. Government and its State Department for ensuring Afghanistan, as well as Gambia, would be able to join us for this international competition this year," said the president of the First Global organization, Joe Sestak, who noted that teams from Yemen, Libya and Morocco would also attend.

"All 163 teams from 157 countries have gained approval to the United States, including Iran, Sudan, and a team of Syrian refugees," said Sestak, a former U.S. Navy admiral and congressman.

"I could not be more proud."

The six girls from Herat, Afghanistan, were reportedly blocked from attending the robotics competition even after two rounds of interviews for a one-week visa.

The rejections appeared to contradict the administration's claim that it wants to empower women globally.

"We were not a terrorist group to go to America and scare people," 14-year-old competitor Fatema Ghaderyan told AFP in Herat.

"We just wanted to show the power and skills of Afghan girls to Americans."

"We cried a lot after we heard our visa was rejected," added 15-year-old Kowser Roshan. "We thought we had good relations with America and expected to be accepted."

They told AFP they had worked for six months on their robot, which they built out of low-tech, recyclable material such as bottles and boxes.

Organiser Ali Reza Mehraban of the Digital Citizen Foundation said it had been especially difficult to find girls in deeply conservative, war-torn Afghanistan whose families would allow them to take part.

When the reversal was announced, Trump adviser and daughter Ivanka Trump tweeted: "I look forward to welcoming this brilliant team of Afghan girls, and their competitors, to Washington DC next week!"

A limited version of Trump's travel ban -- temporarily barring refugees and visitors from Iran, Libya, Somalia, Sudan, Syria and Yemen -- recently took effect, after the U.S. Supreme Court allowed it to be enforced pending a full hearing in October.

Travellers from Afghanistan and Gambia are unaffected by that measure.