Last-minute changes to the Fire & Rescue Services Bill were made to ensure it could reach the statute book before Parliament's summer recess.
Office of the Deputy Prime Minister minister Phil Hope said the bill was not intended to regionalise the service by stealth, despite claims by the Conservatives and Liberal Democrats.
But it does include powers to combine fire and rescue services in cases where they are unable to work together.
He told MPs: 'We accept the argument that councils are in a unique position. Local authorities are the elected bodies representing the people involved in any proposed combination scheme, and they are also the bodies from which the existing fire and rescue authorities are themselves constituted.'