A security expert has claimed that deadly explosions in Brussels prove there exists a "substantial network" of terrorists across Europe. Dozens have been killed after a series of blasts at the Maelbeek Metro station and Zaventem airport.

Matthew Henman, the manager of IHS Jane's Terrorism and Insurgency Centre, said, "It's not a case of a security failure or the fact that the security services maybe should have anticipated it and averted the attack, but rather an indication of the challenge that is faced by the security services across Europe in preventing this kind of attack. You clearly have a very sophisticated network that is capable not only of producing individual attacks like this but a series of attacks which becomes an enormous challenge for the security services".

Henman added: "The Paris attacks showed us that there was clearly a substantial network at play in Europe. So not just the nine attackers, but the support team that drove the vehicles, that provided the vehicles, that sourced the weaponry etc. That was then illustrated when [Salah] Abdeslam was able to go on the run for four months, moving between locations in Belgium, aided by this network, which has now seemingly been able to produce another attack on a lower, but no less significant scale".

Henman also claimed that the explosions could have been planned for weeks, saying that attacks such as these take longer than three or four days to prepare. Some are suggesting that these attacks are a direct response to the arrest of Paris attack suspect Salah Abdeslam.

Belgium authorities have announced a disaster plan in effect in Brussels. Keep up to date with all the latest from the Belgian capital here.