Patients will wait no longer than 13 weeks for scans in NHS hospitals or clinics in England from next April in the government's latest attempt to shorten the periods before treatment can start.

Trusts that fail to meet the target will have to offer appointments elsewhere.

The measure coincides with a report from the Healthcare Commission highlighting variations between trusts in arranging scans and x-rays. Some waits were unacceptable, it said.

A review of 153 acute hospital trusts found that while 25 met the 13-week target for scans, some patients at 67 others waited more than 26 weeks.