The crisis-hit UK National Health Service (NHS) online application system for allocating specialist training posts to junior doctors will be axed, health secretary Patricia Hewitt has announced.

Hewitt also confirmed that criminal activity "may have been committed" after the personal details of hundreds of doctors – including their home addresses, phone numbers and sexual orientation – were made available online by the Medical Training Application System (MTAS) last month.

The security breach is already being investigated by the Information Commissioner's Office, and the health secretary said details had now been passed to the police.

MTAS had already sparked protests by doctors after problems with the online application process itself – for which the government was forced to apologise. The British Medical Association warned that the system had "descended into pandemonium" when it appeared that applicants had been wrongly denied interviews for posts. The system had crashed under the pressure of thousands of junior doctors trying to submit applications simultaneously.

In a written ministerial statement, Hewitt said MTAS would no longer be used for matching candidates to training posts.

Information security specialists MWR Infosecurity had completed a full review of the system and action had been taken by the contractor, Methods, to address the weaknesses identified.

"The site was therefore re-opened last week, restricted to postgraduate deaneries only, to support the next steps in the recruitment process," Hewitt said.

But she conceded that the website would no longer fulfil its original purpose of allocating specialist training places to junior doctors. "Given the continuing concerns of junior doctors about MTAS, the system will not be used for matching candidates to training posts, but will continue to be used for national monitoring," she said.

An additional 15,000 first-round interviews had been arranged for junior doctors following a review of the application process, she added.

Details of the security analysis conducted by MWR Infosecurity had been supplied to the police after the investigation revealed signs of criminal activity.