Security has been tightened around the London site for Europe's biggest arms fair as it opens on Tuesday.
Police patrol the ExCel centre where the arms fair is being held
Among the items on display are warships, a Eurofighter Typhoon jet and an Apache attack helicopter.
Government buyers from countries including Algeria, Angola, Colombia, Pakistan and India are expected to come and browse at the ExCel centre in Docklands.
But critics of the show say it will attract countries with deplorable human rights records and are threatening to disrupt it.
More than 2,600 security guards and officers are to police the site, including 25
Ministry of Defence police officers who will be inside the exhibition centre.
THE ARMS TRADE
Key facts and figures from a business worth almost £19bn a year worldwide
The policing bill would run to more than £1m, said Metropolitan Police deputy assistant commissioner Andy Trotter.
"Our concern would be if the demonstration turns into riots or damage and we have got
to be prepared to deal with that," he said.
More than 50 arrests of mainly protesters were made in the run-up to event.
The Campaign Against the Arms Trade (CAAT) said the group would attempt to disrupt the event in a number of
ways, including holding a procession to the fair on Tuesday morning.
Some individuals were expected to try to gain access to the high-security event,
a spokesman said, but the CAAT action would be non-violent.
"This arms fair is a bringing together of companies and countries with
terrible track records," he said.
"First and foremost we hope we will get it cancelled, or create a public
outcry big enough to make sure it doesn't happen again."
UK DEFENCE INDUSTRY
Its biggest customer is the UK government, which last year placed orders worth £13bn
The UK is the world's second biggest arms exporter, behind the US
It claims to employ 350,000, spread over 11,000 firms
In 1999 defence spending accounted for 2.6% of GDP
A spokesman for organisers Defence Systems & Equipment International insisted the event, which was opened by UK Defence Secretary Geoff Hoon, was not an arms fair.
"This is an exhibition, mainly for contractors and sub-contractors. It's an
industry-to-industry show," he said.
Every exhibitor signed a form saying it would not bring illegal weapons
systems, and these were monitored by the MoD, he said.
About half the exhibitors are British firms, with 20% from the US and the
remainder from other Nato countries.
The organisers have emphasised that 90% of exhibits are not arms but military support equipment.
A spokesman for the MoD's Defence Export Services Organisation said: "We have strict export licence criteria and going to the exhibition in no way implies
that you can buy the equipment.
"Defence brings £5bn a year to the UK and benefits between 70,000 and