BUENOS AIRES (Reuters) - Argentina revoked the credentials of some activists who had been accredited by the World Trade Organization (WTO) to attend its ministerial meeting taking place in Buenos Aires next month, the foreign ministry and civil society groups said on Thursday.

The 63 activists who had their accreditations rescinded were largely affiliated with the Our World Is Not for Sale network, said organizer Deborah James. The group opposes “corporate globalization” and has staged protests at previous WTO meetings.

A spokeswoman for Argentina’s foreign ministry told Reuters some individuals were not allowed to attend because they were determined to be “more disruptive than constructive.”

WTO meetings often attract protests by anti-globalization groups, but they have remained largely peaceful since riots broke out at the 1999 meeting in Seattle.

“We’ve never had this happen before. It’s totally unprecedented,” James, who is also director of international programs at the left-leaning Center for Economic and Policy Research, said by telephone from Washington, D.C.

The group posted a public letter including an email the WTO sent to certain participants on Wednesday discouraging them from traveling to Argentina for the Dec. 10-13 meeting to avoid being turned away at the airport.

The Geneva-based WTO did not immediately respond to request for comment after normal business hours. The Financial Times on Thursday quoted WTO spokesman Keith Rockwell saying the WTO had asked the Argentine government to reverse the decision.

Argentina’s President Mauricio Macri has promoted free-trade policies since taking office in December 2015, and Argentina will host global events as chair of the G20 group of major economies next year.

During protests that coincided with a World Economic Forum event in Buenos Aires earlier this year, security forces used water cannons and tear gas to control picketers who had blocked a highway.

James said it was unusual for a government that had agreed to host an international gathering to deny entry to people who were accredited by the host organization.

The activists represented 20 different groups, including Friends of the Earth International and Global Justice Now. Nearly 500 civil society groups registered.

James said she could not tell why some members were rejected and others not, and said she planned to attend.

“They’re not blacklisting me, and I’m the organizer.”