Green MP Caroline Lucas has urged ministers to put protections for animal sentience into Brexit legislation amid fears the Government's plans will not come into effect quickly enough.
She said her "belt and braces" approach would provide legislative certainty, as she warned MPs that plans from Environment Secretary Michael Gove may not be on the statute book before Britain leaves the bloc.
Ms Lucas was reiterating calls she made at a previous stage of the European Union (Withdrawal) Bill, which would have transferred an EU protocol recognising animals as sentient beings into domestic law.
The vote against her amendment prompted a social media backlash, while Mr Gove has since tabled a draft Bill enshrining animal sentience into UK law post-Brexit and introducing jail sentences of up to five years for animal abusers.
Speaking at the Bill's report stage, Ms Lucas said: "The new laws on sentencing are certainly to be welcomed, but I don't see why we have to have an either or.
"What I am simply trying to do is to make sure that there isn't a legislative gap, because I don't have confidence - maybe those on the other side do - but I don't have confidence that this new Bill, brought forward by the Secretary of State, is likely to be on the statute books by the time we leave the EU, if that's what happens.
"I simply want to make sure that there is legislative certainty, belt and braces, by making sure that we have my amendment in that EU Bill as well."
She also criticised the Tories, saying animal welfare had not been promoted in the past as a "lack of political will here rather than because the EU itself has prevented it".
Brighton Pavilion MP Ms Lucas added: "If you expend enough political energy within the EU, you can get those kind of derogations, as there was for example on seal fur.
"We could have done the same on things like live animals. We chose not to.
"Indeed ... there's actually a record of this Government of not supporting tighter legislation when it comes to the live animal transport trades.
"So I will not stand here and listen to people on the other side of the House pretending their new-found detoxification strategy for the Tory Party is some kind of reflection of a long-held belief on animal welfare."
Ms Lucas has tabled a fresh amendment at the Bill's report stage urging the Government to transfer the EU protocol into UK law.
She indicated she would push her amendment to a vote.
Liberal Democrat MP Tom Brake said: "Would it be cruel of me to remind the House that (Mr Gove) of course is on record having made a solemn pledge to support in this case the Foreign Secretary in his bid to be leader, but then ended up stabbing him repeatedly in the front."