Boris Johnson said access to EU markets would be "absolutely protected" while the UK can strike new deals elsewhere.

NFU Cymru President John Davies said farmers had no certainty about access to EU markets until "the ink is dry" on a post-Brexit trade agreement.

He said securing a withdrawal agreement was only the first stage of Brexit.

It follows Mr Johnson's visit to Wales on Monday to launch the Conservatives' Welsh manifesto for next month's general election.

Speaking at Bangor-on-Dee, near Wrexham, he said: "The great thing about the deal that we have is that it is zero tariff - it is zero quota.

"It means that we can come out with a deal which keeps farming absolutely protected for its markets in the EU.

"[It] enables us to protect those arrangements but also enables us to get on to find new markets for Welsh produce."

The withdrawal agreement with the EU, which Mr Johnson hopes will be passed by Parliament following the election, guarantees no tariffs or quotas during a transition period due to end in December 2020.

A political declaration on future relations beyond that date states that "the economic partnership should through a Free Trade Agreement ensure no tariffs, fees, charges or quantitative restrictions across all sectors".

However, the commitment is not legally binding and has yet to be negotiated.

Mr Davies said: "This can only amount to a statement of intent as to our future trading relationship with our nearest and most valuable export market.

"Until such a time as the trade negotiations are concluded and the ink is dry on the page, then I am afraid that we do not have any certainty about the level of access we will have to the markets of the EU27."

The NFU Cymru leader added that even if a free trade deal could be struck, he was concerned about the potential impacts of regulatory checks on trade with the EU.

Welsh Liberal Democrat leader Jane Dodds said the prime minister was "either deliberately misleading people or does not know what his own [EU] Withdrawal Agreement entails".

"The only way to guarantee tariff and quota free access to European markets for Welsh farmers is to remain in the EU," she said.

Analysis by Chris Morris, BBC Reality Check correspondent

The aspiration to have a zero-tariff, zero-quotas trade deal is all very well, but it's not the only - or even the most important - part of the equation.

The EU knows Boris Johnson wants to have the freedom to diverge from EU rules and regulations.

But the more the UK does that in the future, the more complicated its access to the EU single market will be.

That applies to farmers just as much as anyone else, so no one can guarantee at this stage that Welsh farming will be "absolutely protected" for its markets in the EU.