London: When not in use, your webcam should be covered or disconnected as hackers could use them to spy on you, a charity has warned.
Childnet International says webcams should be disconnected when not in use, and teenagers should not leave webcams in bedrooms or other private areas.
The chief executive of Childnet International, Will Gardner, says it has anecdotal evidence of webcams being hacked, although it is rare.
"It`s difficult to say how commonplace it is, but it can happen," he was quoted as saying.
"The key advice is not clicking on links or opening attachments from people you don`t know.
"Pointing your webcam at a wall or covering it up can be good practice, and closing the laptop lid.
"There`s a range of practical measures to make sure that if somebody did manage to infect it, they wouldn`t be able to see anything."
A BBC Radio 5 live investigation found sites where hackers exchanged pictures and videos of people captured on their own webcams without their knowledge.
House of Commons Home Affairs Committee Chairman Keith Vaz urged teachers to talk to pupils about the dangers of using webcams, and computer manufacturers to improve security for users.
"What surprises me is the ages of the some of the people involved. This is an area that the committee didn`t even look at as it didn`t come to its attention until now.
"It is important that our teachers and the education system wakes up to the importance of advising young people on what could and couldn`t happen," he said.
"Manufacturers should look at the ways to ensure that computers and webcams themselves can alert people that they are still on - perhaps with a bleep - so that the users can realise it`s still on, and make sure it`s switched off," Vaz said.
But some experts have expressed doubts about how widespread webcam hacking is and stressed that anti-virus software plays a vital role in preventing it.
The BBC Radio 5 live team found a thriving black market where access to compromised computers was bought and sold for a few pence.
Hackers are able to gain access to victims` computers using a piece of malicious software (malware) called a remote -access Trojan (Rat).
Many Rats now include a function allowing a hacker to access the victim`s webcam without their knowledge.
The malware is spread in infected files or by tricking the victim - known as a "slave" or "bot" - into visiting a specific webpage.
A BBC Radio 5 live producer posing online as a computer security enthusiast made contact with several webcam hackers from the UK and around the world.
At least one of them has since been arrested on suspicion of cyber-offences, the report said.
The investigation uncovered websites where hackers share pictures and videos of their victims.