Rainer Wendt, the head of one of Germany's biggest police unions, DPolG, has described the Brussels bombings as an "alarm signal" for all of Europe. "We have to expect a long period of terror," he told the "Passauer Neue Presse" newspaper - before adding that an attack on a German city appeared inevitable at some point.

"London, Madrid, Paris, now Brussels. German cities won't be spared in the long run," he said. "We've been lucky so far." He added that the immediate priority was to catch the Brussels suspects still on the run, some of whom may have crossed into other countries.

Wendt called for Germany to accelerate the reinforcement of security precautions in the country.

German federal police are currently ramping up their specialist anti-terror units, and stocking up on equipment like bulletproof vests and helmets and armored vehicles - something Wendt believes could have been done much earlier.

"That's all happening now very hectically, even though the growing threat has been known for years," he said. "Up to now federal police officers have had to drive to border controls in an ordinary VW bus."

More money

Wendt also took a swing at the new budget plan presented by German Finance Minister Wolfgang Schäuble on Wednesday. "Additional billions are being spent on a solidarity pact in the federal budget. But I'm waiting in vain for a billion-euro package for domestic security."

The German government said it was increasing its domestic security budget by 2.1 billion euros by 2020 in Wednesday's new plan. The Finance Ministry said this amounted to an "above average" increase, and underlined that the focal points would be "strengthening the security forces and the federal police."

But GdP deputy chairman Sven Hüber said the new funds were far from adequate. "The money that Schäuble is making available now is mainly to finance the 3,000 new posts that [Economy Minister Sigmar] Gabriel forced through in a coalition meeting in December," Hüber told DW. "But that only closes the gap that's been in the federal police since 2008."

"That doesn't cover all the extra demands that have developed since then - for everything from personal protection abroad to deportation of rejected asylum seekers," he added.

In December last year, a month after the Paris attacks, German Interior Minister Thomas de Maiziere presented a new special counter-terror unit called the "BFE+" (an abbreviation that stood for "evidence collection and arrest unit plus"), which was intended to support the GSG 9 force established in 1972. BFE+ is designed to deal with simultaneous machine gun attacks in multiple locations, such as those that happened in Paris and Brussels.

"The problem is that those officers will then be missing in other places," said Hüber. "Now we're supposed to send 200 officers to Greece for example [to cope with the refugee influx]."

More cooperation

Wendt also said that the European Union's partners and its security forces needed to work closer together in future - he said data exchange between the police, the judiciary, and the EU authorities across the bloc could be improved.

Wendt was backed up by Oliver Malchow, his counterpart in Germany's other major police union, the GdP, who said in a statement, "Europe's member states need to begin to grasp that only a joint interior, judicial, and security policy, unfettered common data exchange and border-less police cooperation can protect people in Europe better from Islamist terror."

In December last year, a month after the Paris attacks, German Interior Minister Thomas de Maiziere presented a new special counter-terror unit called the "BFE+" (an abbreviation that stood for "evidence collection and arrest unit plus"), which was intended to support the GSG 9 ("border patrol troop 9") established in 1972. It is specifically designed to deal with simultaneous machine gun attacks in multiple locations, such as those that happened in Paris and Brussels.

Suspicious car stopped in Bavaria

Meanwhile, three Kosovan men were detained on suspicion of terrorist-related activity on the highway between Salzburg in Austria and Munich on Tuesday evening. But state prosecutors said on Wednesday that initial suspicions had not been confirmed and the men had not been charged.

State police said that the three men have been stopped following an anonymous tip-off on "suspicion of preparing a serious state-threatening crime," but they have underlined that there is no evidence as yet of a connection with the attacks in Brussels.

According to local state broadcaster "Bayerischer Rundfunk" the men had connections with Belgium. The car they were driving was registered in Belgium and the three men - two brothers and a companion, all aged between 36 to 46 - worked for a Belgian construction company.

The men were also carrying 10,000 euros ($11,200) in cash, which they said they needed to buy tools and a car.

A Bavarian police spokesman confirmed to DW that the details of BR's report were correct.

One of the brothers was also found to have an outstanding arrest warrant after absconding following his scheduled deportation to Kosovo.