Threats made towards MPs on social media around Wednesday's vote on extending Britain's military role in Syria are being assessed by the Metropolitan Police.
Scotland Yard said in a statement that it knew of a number of remarks made online and that it was busy evaluating these for possible investigation.
The Met said: "Police are aware of a number of threats made on social media relating to Members of Parliament. An assessment of these threats is ongoing."
Momentum, a rising left-wing faction within the Labour Party which seeks to organise local party members, has been blamed for "reprehensible comments" and "intimidation".
Stoke-on-Trent Central MP Tristram Hunt called for the party leadership to disown Momentum.
"We need the office of the leader of the Labour Party to say Momentum is nothing to do with us, it's nothing to do with the Labour Party," he told Channel 4 News on Thursday.
He said there had been some "reprehensible comments from those involved in it but also intimidation of MPs and particularly intimidation of female Labour MPs".
Neil Coyle MP told Sky News on Thursday: "Unfortunately some of those people around (Jeremy Corbyn) are doing things he finds unacceptable".
Walthamstow MP Stella Creasy has become a particular target for online abuse and threats that she will be deselected as an MP. Shadow Chancellor John McDonnell said this was "not acceptable".
"I tweeted yesterday, because there was people putting it around that there was some attempt to deselect Stella Creasy. I tweeted yesterday there is no way she should be deselected, she’s an excellent MP and she has my support, as she has in her local constituency," he said.
Jeremy Corbyn faces his first electoral test as Labour leader on Thursday when votes cast in the Oldham West by-election are counted overnight.