Some 18 percent of US Internet users have had important personal data such as bank account information stolen and the problem appears to be getting worse, a survey showed Monday.

The Pew Research Center study carried out in January showed a sharp increase from mid-2013, when 11 percent reported being victimized.

The survey also found 21 percent reported having email or social network accounts compromised, the same percentage as last year.

The findings come amid growing concern over the "Heartbleed" vulnerability discovered earlier this month, and months after US retail giant Target acknowledged millions of customers may have had payment cards compromised.

"As online Americans have become ever more engaged with online life, their concerns about the amount of personal information available about them online have shifted as well," the Pew researchers wrote.

"Internet users have become more worried about the amount of personal information available about them online -- 50 percent reported this concern in January 2014, up from 33 percent in 2009."

The report is based on a survey of 1,002 adults from January 23 to 26, including 820 Internet users. The margin of sampling error for the Internet users is estimated at four percentage points.

'Heartbleed' hits 1.5 million users of UK parenting website
London (AFP) April 14, 2014 - British parenting website Mumsnet is the latest organisation to have been hacked due to the "Heartbleed" bug, founder Justine Roberts revealed on Monday.

"Last week we became aware of the Heartbleed bug and immediately applied a fix to close the OpenSSL security hole," she said in a statement.

"However, it became apparent that users' data submitted via our login page had been accessed prior to our applying this fix."

All 1.5 million registered users were asked to change their passwords, and Roberts did not know how many users had had data stolen.

"The worst case scenario is that the data of every Mumsnet user account was accessed," she said.

"It is possible that this information could then have been used to log in as you and give access to your posting history, your personal messages and your personal profile, although we should say that we have seen no evidence of anyone's account being used for anything other than to flag up the security breach."

The website offers users a forum in which parents can ask for, and pass on, advice about bringing up children.

Officials in Ottawa on Monday announced personal data for as many as 900 Canadian taxpayers had been stolen after being made vulnerable by the bug.

The recently-discovered flaw in online-data scrambling software OpenSSL allows hackers to eavesdrop on online communications, steal data, impersonate websites and unlock encrypted data.

Computer security specialists, website masters and others became aware last week of problems posed by the "Heartbleed" bug after several reports of hacking.