Belgian authorities have prevented several terrorist attacks in recent months, a Belgian newspaper said on Saturday.

A report in the daily L'Echo cited unnamed sources who likened the foiled attacks to a deadly shooting at the Jewish Museum in central Brussels on May 24 which left four people dead.

Authorities believe that the suspect in the Brussels attack - Frenchman Mehdi Nemmouche - had links to Islamist extremists in Syria. He was recently extradited from France to Belgium where he faces charges of "murder in a terrorist context."

According to the sources of the Belgian newspaper report, authorities believe there are links between the planned terrorist attacks and the jihadist group "Islamic State," which has taken over large swathes of territory in Syria and Iraq.

Roughly 400 Belgians are believed to have travelled to Syria to fight alongside jihadist groups, L'Echo wrote. Police have been surveilling several of the 90 who have returned so far.

"Our starting point is that among them, one out of nine aim to carry out an attack," L'Echo quoted an unnamed source as saying. "That is a conservative estimate, if you also take into account the people who help them."

The federal prosecutor, Jean-Pascal Thoreau, later confirmed the report, saying: "We are paying full attention to the issue of former combatants."

"We are collaborating with the security services, and that has led to several operations and arrest warrants."

Many Western countries have expressed concern at the rising number of Islamist extremist sympathizers who have traveled to the Middle East to support IS. They also fear the possibility of the jihadists returning home to carry out terrorist attacks. Germany, for its part, recently banned all Islamic State activities, including any sign of affiliation with the group.

jng/kms (dpa, AFP)