The leader of Welsh Labour has backed Jeremy Corbyn’s decision to remain neutral in any fresh referendum campaign even though the party in Wales has pledged to fight for remain.

As both Labour and the Conservatives launched their manifestos in and around Wrexham, a key election battleground, the Welsh Labour leader, Mark Drakeford, said Corbyn’s stance could help heal a divided UK.

Though Wales as a whole voted for leave, the Welsh Labour manifesto says it would campaign “unapologetically, unreservedly and enthusiastically to remain” if there were a second referendum.

Drakeford said: “Wales’s economy is more exposed than any other part of the UK to the effects of a hardline Boris Johnson Brexit. We will campaign to persuade people in Wales to remain.”

Insisting that he wasn’t disappointed at Corbyn’s neutral stance, Drakeford said: “In a deeply divided country where a Labour government will have to heal those wounds, Jeremy saying he will hold himself in readiness for whatever people decide will help in that healing process.”

Unveiling the Welsh Labour manifesto at a college in the centre of Wrexham, Drakeford said that many of the radical policies that the UK Labour party wanted to introduce in England had already been implemented in Wales, such as free prescriptions, free school breakfasts, free hospital parking, the abolition of right to buy, keeping guards on trains and banning fracking.

He claimed UK Labour’s plans to end austerity would mean a £3.4bn increase to Wales’s annual budget. The party promised to revive the stalled Swansea Bay tidal lagoon project, work with people on the island of Anglesey to “maximise its potential for new nuclear energy” and invest in railways.

Drakeford said: “The destructive policies of the UK Conservative government have left our communities damaged, our economy one of the most unequal in Europe and the UK ill-prepared for the climate emergency it now faces. This election is the chance to put that right.”

Corbyn did not attend the Welsh Labour event but over at Wrexham racecourse in the neighbouring constituency of Clwyd South, Boris Johnson was present at the Welsh Tory manifesto launch.

Fresh from a photo opportunity at the Royal Welsh Winter Show in which he sheared a sheep, the prime minister insisted that new, profitable markets would open up for Welsh farmers after Brexit.

Boris Johnson trims a sheep at the Royal Welsh Winter Show in Llanelwedd before attending the Welsh Tory manifesto launch. Photograph: Reuters

He said: “We will make sure we open up new markets for Welsh lamb. Why should New Zealand be supplying huge quantities of lamb to China when as far as I know Wales is closer to China than New Zealand is?” He then got a Tory supporter in the audience to google whether Wales was in fact close to China.

Johnson said the Tories would protect Welsh steelworkers and would tackle congestion at the notorious Brynglas tunnels on the M4 in south Wales, which he compared to the blocked up nostrils of a Welsh dragon.

He rejected the notion that the Tories should be ashamed of the impact austerity has had on Wales, arguing the Conservatives had to run the economy sensibly after Labour mismanagement but said Wales could look forward to an “infrastructure revolution”.

The Tory leader at the Welsh assembly, Paul Davies, described the Labour-led Welsh government as “Corbynite” and attacked its record on health and education. He claimed that unlike Labour, the Tories in Wales respected the people’s decision to leave.