Over half of all Conservative backbenchers rebelled against David Cameron on the vote to ban foreign criminals claiming their right to a family life to avoid deportation, Labour said.
Anticipating a rebellion, Downing Street ordered Conservative ministers to abstain.
The Labour Whips' Office tweeted:
Initial count is that around 85 Tory MPs, over half of all tory backbenchers, rebelled against @david_cameron on Raab's Amdt.
Hearing that Tory whips were preventing Tory MPs voting against Raab Amdt even though Gov said it was illegal - shambles
The immigration debate is underway in earnest in the Commons, exposing the rift which cuts through the Conservative Party in Westminster.
The Immigration Bill was shunted into the sidings over Christmas while ministers worked out how to head off a rebellion they saw coming.