BOSTON (Reuters) - Hackers have built a virus that attacks Apple Inc.'s iPhone by secretly taking control of the devices via their Internet connections, security experts said.

The virus has been detected in the Netherlands and can only attack iPhones whose users have disabled some pre-installed security features, according to analysts monitoring the progress of the virus.

The hackers are trying to use the virus to obtain passwords to banking sites, according to Graham Cluley, a researcher with anti-virus software maker Sophos. When an iPhone user tries to access a bank website, the Duh Worm directs the browser to a look-a-like site controlled by the hackers, Mr. Cluley said.

A spokeswoman for ING Group said the Dutch banking giant discovered a criminal network that attempted to steal banking credentials via hacked iPhones. Dutch clients of ING have been targeted, but there was no indication that clients outside the Netherlands have to worry, she said.

ING has not received any reports from clients that their credentials have been lost, but the bank was monitoring client accounts for suspicious transactions, the spokeswoman said.

The only iPhones that are vulnerable to the Duh Worm are "jail broken" phones, where users disable key Apple security features to get around the terms of usage agreement that they are designed to enforce, analysts said.

For example, Apple prevents users from switching service providers to unauthorised carriers and limits users to the approximately 100,000 programmes that the company has vetted for installation on the device.

"The vast majority of customers do not jailbreak their iPhones, and for good reason. These hacks not only violate the warranty, they will also cause the iPhone to become unstable and not work reliably," said Apple spokeswoman Natalie Harrison.