Families have been left fuming after their children's personal details were published online.
The names, addresses, telephone numbers and email accounts of more than 50 netball club members, some as young as 11, were published after an internet blunder.
Parents were stunned to hear the information, which should have been secured on the Charville Netball Club website, was available for anyone to view for nearly a week before being pulled down.
Cheryl McGinty, who lives in Northolt but whose teenage daughter has attended the club in Ruislip for more than a year, said: "We had no idea they were up on the internet, and even if they were on a secure site, it's not good practice at all, especially when we have a lot of stuff on the computer and we make sure that we never give personal details out.
"I'm very disappointed with this as we are ex-directory and pay extra money to have anonymous caller reject to make sure that our details are not advertised just anywhere.
"As a parent you're always concerned about your child and we make sure she doesn't give out her personal details online."
It is believed the brother of a 13-year-old girl who no longer attended the club made the alarming discovery after typing in his name and stumbling across his sister's details.
Now the chairman of the club based at Queensmead Sports Club, with members across Ealing, , Hillingdon and Rickmansworth, has vowed never to post sensitive information online. Terry Tilbury said: "The information was placed on what we believed was a secure area of our website where only a handful of committee members could view the details.
"I was devastated to find out that the information wasn't secured.
"We have now rectified the problem but this has left me with no confidence or trust using the internet and there is no way we would post sensitive information intentionally."