LONDON — A huge arms fair is quietly taking place in London this week, and a group of activists - including some of the artists involved in Banksy's Dismaland - aren't pleased.

The Defence and Security Equipment International (DSEI) trade fair, which is apparently "the largest fully integrated defence and security show in the world," is happening at the city's ExCel centre from Tuesday until Friday (Sept. 18).

Featuring some 1,500 exhibitors from over a hundred different countries, the exhibition is split into land, sea, air and unmanned zones, among others.

As the conference opened, though, a series of posters protesting its presence in the city cropped up across the transport network.

Organised by Special Patrol Group, they're drawing attention to the event and asking commuters to help stop it.

"This September, a swarm of arms dealers will be descending on the DLR," one reads, copying the language of a traditional Tube advert. "These visitors make huge amounts of money from weapons and equipment that kills people in wars all over the world."

"Customers are requested to help stop the arms fair."

Customers are requested to help stop the arms fair. #StopDSEI pic.twitter.com/F44JL4XNWK — Special Patrol Group (@SpecialPatrols) September 14, 2015

"Britain has sold £12bn of arms to some of the world’s worst human rights abusers," another says.

Selling arms is Great Britain, bombing is Great Britain. #StopDSEI pic.twitter.com/Xd4cH5bFo0 — Special Patrol Group (@SpecialPatrols) September 14, 2015

Curator Gavin Grindon, who put together the "Cruel Designs" exhibit at Dismaland, which featured spoof adverts and police hardware, said it was a natural step to target the fair.

"The posters appeared today to commemorate the opening of DSEI, who don’t seem to have done much advertising of their own,” he told London 24.

Artists in Banksy's #Dismaland visit London for opening day of DSEI arms fair. Put up ads across city. #StopDSEI pic.twitter.com/oplIF7m6zH — Gavin Grindon (@GavinGrindon) September 14, 2015

A further protest was staged at the site of the exhibition Monday, with members of protest group Campaign Against Arms Trade present.

This morning death visited @ExCeLLondon which will host 30,000 arms dealers fuelling conflict & destruction #StopDSEI pic.twitter.com/yvd6pzEaAA — CAAT (@CAATuk) September 14, 2015

Saudi Arabia, Egypt, Bahrain and Azerbaijan are among the authoritarian regimes invited to the fair this year by the British government, the Guardian reports.

Amnesty International also created a spoof video advertising the fair.

A spokesperson for Transport for London said that the posters were "an act of vandalism which we take extremely seriously."