The government is tonight scrambling to save its plans for rent caps - after a major error was exposed in the legislation.

Fine Gael and Fianna Fail had earlier agreed to stick with a 4% rent cap, but to speed up their introduction in other urban and commuter areas.

However a drafting error means that the 4% cap could be doubled to 8% immediately after the end of the current two-year rent freeze.

Tenants whose rents had not been adjusted for longer than this could face increases even bigger.

This is how the rent cap is to be provided for in law... if you're at the end of a 2-year freeze, t=24 and your rent increase might be 8%... pic.twitter.com/ql2Jh9Qpni

— Gavan Reilly (@gavreilly) December 15, 2016

The Department of Housing has admitted the mistake, describing it as a "technical glitch", and says it hopes to fix the mistake through an oral amendment this evening.

The legislation is being rushed through the Dáil - having already passed the Seanad - in order to give effect to the rent caps before Christmas. 

This means the Seanad cannot be relied on to rectify the mistake, as the Dáil would then have to be recalled again in the days before Christmas.

The error was spotted by Sinn Féin's Eoin Ó Broin, who has described it as a "cock-up".

He says it's a major oversight, which reflects poorly on both Fine Gael and Fianna Fáil who were otherwise prepared to allow it: