Anti-war protestors, fuelled by events in Syria, are expected to be out in greater numbers at this year’s arms fair.

But organisers of the biennial fair, called Defence & Security Equipment International (DSEI), insist buying and selling weapons is about protecting the UK’s national security.

The fair will be held at ExCeL exhibition centre in Custom House for four days from Tuesday.

Although it attracts tens of thousands of delegates – from governments, military organisations, and defence manufacturers – it always becomes a focal point for anti-war protesters who stage a candlelit vigil and demonstrations.

This year, with international attention focused on events in Syria, groups like the Campaign Against Arms Trade (CAAT) are expecting more people to take to the streets.

A spokesman said: “The slaughter in Syria is very much in people’s minds – and yet it seems that Russian companies supplying arms to Syria will be there, together with Israeli companies supplying ‘battle tested’ equipment and companies supplying teargas to governments in Brazil, Bahrain and Turkey, who have used such gas against protesters.”

CAAT is among a coalition of organisations including War on War and East London Against the Arms Fair. Action planned this year includes a demonstration against drones, with a candlelit vigil on the eve of the event outside Royal Victoria DLR in Tidal Basin Road on Monday.

A spokesman for DSEI said: “DSEI provides an important forum in which MOD officials and officers can conduct a large number of meetings with industry in one place. It provides a valuable opportunity to meet with key members of the defence supply chain, manage the cost of programmes and deliver the best possible value to UK taxpayers.”

The event is run by Clarion Events Limited and includes 1,500 international exhibitors who will display a variety of weapons and defence systems for more than 30,000 visitors to see.

Defence manufacturers see the arms fair as vital because it gives them the chance to showcase the latest military hardware and network with potential buyers.