Hotels and Bolshoi evacuated

The Bolshoi theatre was evacuated on Sunday, along with major Moscow shops and hotels, after a series of bomb alerts in the Russian capital, local news agencies reported.

"This is another wave of anonymous calls about bombs... in all 10,000 people were evacuated in Moscow because of these threats," the Interfax agency quoted an informed source as saying.

The bomb alerts came as Russian police detained over 400 activists across the country for holding unauthorised protests against President Vladimir Putin, according to a monitoring group.

Along with the Bolshoi, the GUM and TsUM luxury department stores were evacuated on Sunday along with two top hotels near Red Square and the Kremlin building in the heart of Moscow.

Several cinemas and shopping centres were also evacuated, according to Russian media.

Sunday's alerts were reminiscent of a series of phoned-in false alarms which were raised in September which affected a total of 1.4 million people. No bombs were found then at any of the venues mentioned.

According to the FSB security service, those calls were made by Russian citizens outside the country.

Such anonymous calls diminished in October though did not stop completely.

Russia beefed up security measures after an underground train bombing in Saint Petersburg in April which left 16 people dead and many more injured.

Puigdemont would have to prove a "threat of persecution" in his country of origin and an impossibility of being protected there, Van Den Bulck said.

- What are the implications for Belgium? -

The Spanish standoff is already causing problems for the Belgian government led by Prime Minister Charles Michel, who rules in a coalition with Flemish separatists sympathetic to the Catalan cause.

The French-speaking Belgian leader was quick to stress that his government had "not undertaken any step to encourage Mr Puigdemont's arrival on Belgian soil" and warned him not to expect special treatment.

But Michel's immigration minister Theo Francken, from the Flemish separatist N-VA party, said Belgium could offer asylum to Puigdemont, infuriating Spain.

The EU and its member states have been resolute in their support for Madrid during the Catalan independence crisis, but Michel has been more muted, calling for dialogue to resolve the standoff.