A Hard Brexit pressure group is "heartened" by Theresa May's comments on the UK's split from the EU on Sunday (8 January), despite the prime minister failing to commit fully to breaking from the bloc's customs union.

"We are not in any way disappointed, we're actually heartened by the direction of travel," said Richard Tice, the co-chair of Leave Means Leave.

He added: "She didn't actually really say anything, she just kept repeating what she had previously said.

"The reality is, even when she comes to give her speech later this month, she won't put it out in stark terms of: 'we're going to leave the single market, we're going to leave the customs union'."

Tice's praise comes after May's first interview of 2017 with Sky News' Sophy Ridge. The Conservative premier hinted that the UK government would leave the EU's single market.

"Often people talk in terms as if we are leaving the EU but we still want to keep bits of membership of the EU. We're leaving, we're coming out," she said.

May's remarks come months before the UK government plans to invoke Article 50, the mechanism to split from the EU, and trigger talks with the EU.

The Supreme Court is expected to rule in January whether MPs should have a vote on the issue after an appeal from the government.

Rise, who is also a co-founder of the Leave.EU campaign, said it would be "perfectly acceptable" if the UK ends up trading with the EU under World Trade Organisation (WTO) rules.

"Whilst it's desirable to seek a zero-tariff deal or something close to that, we shouldn't wait more than two years to do that and the EU27 need to be under no illusions that we will leave with or without a deal after two years," Tice said.

"If that means because they can't get their act together, that we just leave and go to WTO rules, which of course is how most countries across the world trade with the EU, then that's absolutely fine, that's perfectly acceptable. That's what businesses should plan towards."

The pro-EU Liberal Democrats, meanwhile, have warned about a "disastrous hard Brexit".

"Theresa May has confirmed she is taking us towards a disastrous hard Brexit that will leave our country poorer and more divided," said Tim Farron, Liberal Democrat leader.

"Reckless plans to leave the single market would deal a huge blow to jobs, investment and the public finances, meaning less funding for services like the overstretched NHS.

"In all this she has Labour holding her hand on the path to Brexit and failing to provide a decent opposition."

May's Brexit plans took a blow last earlier in January when Sir Ivan Rogers quit as the UK's representative to the EU. But Rogers was quickly replaced by another career civil servant, Sir Tim Barrow.