Cinemas have fitted devices to detect customers' camcorders
The government is being urged to make the use of video cameras in cinemas a criminal offence.
Eleven MPs have signed a Commons motion claiming the practice is to blame for about 90% of fake DVDs on sale.
The UK is "pre-eminent" in supplying the European market because, unlike other EU countries, it has not changed the law on filming, it adds.
People have concealed camcorders in popcorn boxes and used mobile phones to record films, campaigners say.
The use of video cameras in cinemas is currently a civil, rather than a criminal, offence.
This means staff can eject customers for it but police cannot arrest them.
The government argues that it is not necessary to bring in a new law, as piracy itself is already a criminal offence.
Lavinia Carey, director-general of the British Video Association (BVA), told the BBC: "Films are increasingly being shown first in Britain and, if they are not, the time gap between them being screened in America and coming over here is narrowing.
"This makes the European market more and more vulnerable to fake films from Britain."
Cinemas have installed camcorder detector devices and issued staff with night vision goggles to spot them being used.
Ms Carey said: "The lengths criminals go to are quite extraordinary. They can stick a camera in their popcorn or can even record using a mobile phone.
"The battery and memory life nowadays allows them to film on their phones for far longer.
"It's very strange that the government will not change the law. The film industry makes a lot of money for Britain and we are not, unlike some others, asking ministers to bail us out."
A BVA survey suggests that the use of illegal DVDs deprived cinemas of £183m last year.
Police seized about three million fake DVDs in the UK in 2007.
In raids last month 30,000 counterfeits, with a street value of more than £90,000, were discovered in London.
The trade in copied films is known to fund other types of organised crime, including human trafficking and drug dealing.
In their motion, the MPs are urging the government to follow France, Italy and Spain in banning filming in cinemas.
It notes "that camcording in cinemas is the source of 90% of first-release fake DVDs seized and illicit film files on the internet".
It adds that "camcording in cinemas is not a criminal offence, making films particularly vulnerable when they are premiered in the UK".
A spokesman for the government's Intellectual Property Office said: "We recognise that the industry attaches great importance to this issue that costs millions of pounds in lost revenue each year.
"There is legislation already in place to deal with this issue on a criminal and civil level."
The motion has been signed by Liberal Democrats John Barrett, Jeremy Browne, Sandra Gidley, Jo Swinson, and Steve Webb, Labour's Tom Clarke and Ann Cryer, Conservatives John Bercow, Hugo Swire and Peter Bottomley and Scottish Nationalist Angus MacNeil.