A Belgian police officer stands guard outside the Grand Mosque in Brussels, Belgium, November 26, 2015.

The Great Mosque of Brussels was evacuated and 11 people decontaminated Thursday after the discovery of a suspicious package containing white powder as the EU capital remained on highest possible terror alert.

“A parcel was found at the entrance to the mosque and found to contain white powder. We are taking all preventative measures in case it is anthrax but it is a precautionary measure,” said fire services spokeswomen Anne Wibin, who was at the scene.

The mosque, the city’s biggest, is located just a few blocks from the major EU institutions and many embassies and was cordoned off by police and firemen, some of them in white hazard materials suits.

The alert came with Brussels on maximum security levels in the wake of the Paris attacks on November 13, with two Belgium-linked suspects still on the run.

Wibin said eleven people, including two police offers, were decontaminated as a precautionary measure.

“A package was found with several envelopes one of which contained a powder, evidently suspect in the circumstances,” she said.

“The powder has been partially tested and it has been found to be not radioactive,” she said, adding that no possibility was being ruled out.

“People in direct contact were isolated and decontaminated and also those who were in indirect contact.”

“There is absolutely no danger to anyone,” she added.

A worshipper said the development was worrying given the tensions after the Paris attacks which left 130 people dead when Islamic State of Iraq and Syria extremists, several of them residents of Brussels, went on the rampage.

“I’ve been speaking to the staff on the telephone and was told the imam found the package,” said Mohamed Dahmichi, standing across the street.

“It’s not good. With everything else happening in Brussels at the moment I’m afraid to leave the house these days.

“There was the letter at the mosque in Molenbeek too and now this,” he added.

Earlier this week several mosques in the Molenbeek neighbourhood, seen as a hotbed of extremist activity inspired by ISIS, received threatening letters from a group calling itself “Christian state.”

The Great Mosque, given as gift to Saudi Arabia by Belgium, sits on a corner of Cinquantenaire Park where many of the thousands of EU staff take a lunchtime break and families bring their children to play.

It is no more than 200 meters from the top EU institutions — the European Council and the European Commission — plus other offices and many embassies.

Troops and armed police have been out in force in Brussels since Saturday, with the authorities due to review the top level four security alert on Monday.

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