OPEC has denied media access to reporters from Reuters, Bloomberg and the Wall Street Journal to report on oil policy meetings in Vienna this weekend, reporters, Bloomberg and people familiar with the matter said on Friday.

The three media organizations are among the world’s leading suppliers of financial news and information. They report on the outcome of policy meetings between OPEC and its allies, where ministers make decisions that impact the price of the world’s most traded commodity.

The Organization of the Petroleum Exporting Countries and its allies is a group known as OPEC+ and includes top oil producers Saudi Arabia and Russia. Ministers from the group, which pumps more than 40% of the world’s oil supply, are scheduled to gather on Saturday and Sunday for regular biannual meetings.

OPEC staff declined on Friday to give media accreditation to Reuters journalists to cover the event. The staff handling media accreditation at one of Vienna’s luxury hotels said they could not issue accreditation without an invite. They did not comment when asked why Reuters reporters received no invites.

OPEC has not responded to requests for comment from Reuters this week on why it has not invited or accredited Reuters reporters for the meet.

“We believe that transparency and a free press serve both readers and markets, and we object to this restriction on coverage,” a spokesperson for Reuters, the news and media division of Thomson Reuters (NYSE:TRI) Corp, said on Friday.

“Reuters will continue to cover OPEC in an independent, impartial and reliable way in keeping with the Thomson Reuters Trust Principles.”

A reporter from Bloomberg was also denied accreditation on Friday, a person familiar with the matter said.

A Bloomberg spokesperson confirmed on Friday the company has not been given accreditation to cover the OPEC meeting.

The Wall Street Journal did not respond to a request for comment.

Reporters from the three outlets, many of whom have been covering OPEC meetings for years, did not receive invitations from OPEC ahead of the meeting.

Without accreditation, journalists cannot enter the OPEC Secretariat where the ministers meet, or attend press conferences during the event.

Reporters at other media outlets including trade publications Argus and Platts received accreditation on Friday. Argus confirmed its reporters have been accredited and will attend. Platts did not respond immediately to a request for comment.