BRUSSELS // Belgian investigators on Tuesday busted an Islamic extremist network plotting an attack in Belgium, rounding up 10 suspects in Belgium, the Netherlands and Germany as terrorism fears mount in Europe.
"There were plans aimed at committing an attack in Belgium by an international terrorist group using for this purpose an extremist internet site, Ansar Al Mujahideen," the Belgian prosecutor's office said in a statement.
It said Belgian investigators had led an international inquiry from 2009 into a suspect network largely based in the northern port city of Antwerp.
"The target of the attack was not yet specifically determined," the prosecutor's office said, but there were "sufficient facts" to justify the raids.
No extra security measures have been decided to date in Belgium, a spokesman for the government's crisis centre said.
Most arrests took place early Tuesday in several districts of Antwerp, home to both large Jewish and Muslim communities.
On Belgium's VTM television network, police were seen walking off with a young bearded man wearing handcuffs.
Dutch prosecutors said three men aged 25, 26 and 28 were arrested in Amsterdam on a request from Belgium. The detainees, all Dutch nationals, will soon be extradited to Belgium, said spokesman Wim de Bruin.
In Germany, a 31-year-old was arrested in Aachen, DPA agency quoted police as saying.
In Brussels, a spokesman for the prosecutor said "in total 10 people suspected of preparing an attack in Belgium were arrested in Belgium, Holland and Germany." he said.
Those arrested -- of Belgian, Dutch, Moroccan or Russian nationality -- are also suspected of recruiting "jihadist candidates" and of financing "a Chechen terrorist organisation, the Caucasian Emirate".
The detainees go before an investigating magistrate later Tuesday who decides whether or not to keep them behind bars pending charges.
Belgian authorities said several other people have already been arrested in Spain, Morocco and Saudi Arabia as part of the same probe, conducted in collaboration with other countries and the European Union's judicial cooperation unit Eurojust.
In The Hague, a spokeswoman for the government's anti-terrorism coordinator said there were no plans to raise the level of risk of a terrorist threat which remains "limited".
Europe has been on high alert for several weeks over heightened fears of terrorist attacks and on Monday the cupola on Germany's Reichstag parliament building was closed until further notice to visitors after media reports said the popular tourist site was a potential target for Islamist extremists.
Germany's interior ministry said Tuesday's arrests were not linked to recent security threats in the country.
Danish intelligence meanwhile warned of new information "that foreign-based terrorist groups will try to send terrorists to Denmark to stage attacks" and urged police to be "extremely vigilant" in the build-up to Christmas.
Western security officials have warned that Al-Qaeda may be planning attacks in Europe similar to those that struck the Indian city of Mumbai in 2008.
The United States issued on October 3 a travel alert for its citizens travelling in Europe, citing the risk of potential terrorist attacks on transportation systems and tourist attractions.
Similary alerts were issued by Japan, Sweden, Britain and France.
A plot to blow up cargo planes was uncovered at the end of last month after booby-trapped parcels were found at airports in Dubai and Britain.