Plans to allow the taxman to seize money directly from personal bank accounts have been criticised by an influential group of MPs.
The Commons Treasury Committee has expressed "considerable concern" over the Chancellor's debt collection proposals and called for further scrutiny.
In their report on this year's Budget, the MPs suggested the change could amount to a back-door reintroduction of the discredited Crown Preference rule - which gave HM Revenue & Customs (HMRC) priority access to assets when companies went bust.
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Thousands of people have linked hands on Westminster Bridge in a show of solidarity - one week after the terror attack in the capital.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Engineering firm CH2M won the £170 million contract but have pulled out of phase two of the project over alleged conflicts of interest.