Brussels -- the location of key institutions of the 25-nation EU, the headquarters of NATO and a major European city with a population of one million -- remains "ill-prepared" for a terrorist attack, a key official warned Tuesday as Europe remained on high alert after the London bombings.

Veronique Paulus de Chatelet, governor of the authority covering the Belgian capital, said an attack on Brussels would trigger chaos because plans are not in place to deal with such an event. "Brussels is ill-prepared to confront potential attacks. For most public places there is no plan for emergency services," she told the VRT television station.

She said that all railway stations, metro stops, schools, museums and major shopping centers should draw up plans for how to respond in case of a terrorist attack. Currently of 714 such public places only 83 have such a plan, she said.

An attack would lead to chaos, governor says

"Barely a third of the 68 metro stations are prepared" and "an attack would lead to chaos," said Paulus de Chatelet, head of the administrative area covering Brussels and 19 districts surrounding it.

"The starting point of everything is a map -- that is, where are the entry and exit points, where are there water supplies which the fire services can use?" she added.

But according to VRT, the Brussels subway operator MIVB/STIB said plans are in place for all metro stations, as well as for the network as a whole, and were shared with emergency services.

MIVB/STIB said that hand-written plans of all subway stations were available to the city's fire department and it had a separate internal emergency plan. "It is true that as of today we've computerized one third of the data. That will be the case for all stations by the end of the year," spokesman Kris Lauwers told VRT radio

Brussels firefighters have conceded however that museums, large shops and hospitals are not all up to date with emergency plans, VRT said.

Spread of fear makes capital jittery

The comments came as two alerts in Brussels reflected police jitters following recent events in London, where have left the British capital on high alert.

On Tuesday morning, part of Brussels' Gare du Nord station was sealed off after a suspect suitcase was found. It was blown up by bomb disposal experts, but was found to be empty, the Belga news agency said.

Later in the day part of a key road leading from the capital's EU district into the centre of Brussels was sealed off after a bomb threat, Belga reported citing police.

A company also received a telephone warning that a bomb was about to explode. The road where it is located was blocked for about half an hour, until the all-clear was given.

EU officials only assume measures will be taken

In response to fears that the heart of Europe was vulnerable, a spokesman for the European Commission, the EU's executive arm which employs thousands of staff in buildings dotted around Brussels, said EU institutions are in constant contact with Belgian authorities to ensure security. "If measures do need to be taken, that's to be done by the Belgian authorities and we assume that they will be taken," spokesman Michael Mann said.

As well as the EU commission, Brussels also plays host to the European Parliament and the European Council building, which hosts regular meetings of EU ministers and leaders.

Major cities across Europe have been on high alert since July 7 when a wave of attacks killed 56 people on London's underground train network and a bus. After the London attacks, the bloc asked its top terrorism official Gijs de Vries to assess the emergency response plans of all EU states before the end of the year.