A number of MPs have complained of “vitriolic” abuse and “appalling” correspondence from both opponents and supports of equal marriage.

The Independent has reported that the pressure is greatest on the estimated 80 Conservative MPs who have not stated whether they will support the Marriage (Same Sex Couples) Bill – in tonight’s vote at 7pm.

An anonymous MP has said that some of his colleagues had decided to vote in favour of the bill due to the nature of emails from opponents: “Quite a few of us who were considering abstaining will vote in favour of gay marriage because of the unreasonable nature of the emails we have been receiving. Some of the emails I’ve had are simply appalling and I’m fed up with it.”

Conor Burns, a gay Conservative MP who plans to support the bill, said that he had received unpleasant emails from both supporters and opposition: “The whole thing is deeply unpleasant and people are saying things that you wouldn’t say to people you despised or hated.”

He added: “I don’t know what kind of God some of those people who have contacted me from religious groups believe in – but he’s certainly not compassionate or loving.”

Conservative MP Angie Bray, who has refrained from saying how she will vote, said: “You get emails from one side saying you’re morally deficient if you vote no and emails threatening hell fire and brimstone if you vote yes. It has frankly been an ill-tempered debate on both sides.”

David Burrowes, who has been a major figure in the Conservative Party’s opposition to the vote, said that the supporters of the bill had been vitriolic: “I’ve had death threats, hostility and hate mail. My children have even been told that their dad is a homophobe. There has been abuse and intolerance of both sides.”

An estimated 118 Conservative MPs are expected to oppose the bill in today’s vote.