The Hague (AFP) – Police were on high alert in Amsterdam Wednesday after the Manchester attack, as more than 120,000 people streamed to the Dutch capital to watch Ajax take on Manchester United in the Europa League final.

The match was being shown live from the Stockholm Friends Arena on a giant screen set up in Amsterdam’s famous Museum Square.

But hours before kick-off, police warned the square was already full and they were closing it to all new-comers.

Shortly afterwards, they appealed to fans to stay away from the city all together.

“Don’t come to Amsterdam to watch the match between Ajax and Manchester United. Museum Square is closed to more visitors, and other places are full too,” the Amsterdam police said.

More than 120,000 people had already packed into the city centre, and “knowing that thousands more are on public transport, with others in their own transport, the police are urging football fans still on the road not to come to Amsterdam,” police said.

“Want to see the match on time? Then go and look for somewhere else and don’t come to Amsterdam.”

In the wake of Monday’s attack on a pop concert which left 22 people dead in Manchester, police have “deployed an immense number of officers,” a city official said earlier, quoted by the De Telegraaf newspaper.

Dutch anti-terror chief Dick Schoof said late Tuesday after meeting police and event organisers that all parties “are on extra alert”.

But unlike in Britain, Schoof has not increased the terror threat level to maximum, saying he would only do so “if we have information about an actual attack, which we don’t”.

Schoof pressed people “to be alert, keep an eye on things and report any suspect behaviour immediately”.

“Better one warning too many, than one too few,” Schoof added.    

Amsterdam’s mayor Eberhard van der Laan had already announced emergency measures Monday, before the Manchester suicide bombing.

“Chances are, judging by experience over the last few years, that a huge number of Ajax fans will gather in the city,” Van der Laan said in a letter announcing the measures.

“There is a chance that public order will be disturbed and that cans, glasses and bottles will be thrown, vandalism will happen… and fireworks set off,” the mayor said.