Exclusive: Jeremy Corbyn distances himself from comments by a senior member of his own Brexit team.

Shadow International Trade Secretary Barry Gardiner called repeatedly on Monday for Britain to leave the customs union, describing continued membership as a "disaster."

However, Corbyn's spokesman tells Business Insider it is wrong to "sweep options off the table."

Corbyn's intervention leaves Labour's Brexit policy up in the air.

LONDON — Jeremy Corbyn opened a fresh Brexit split inside Labour today after distancing himself from a call by his own Shadow International Trade Secretary for Britain to leave the customs union.

On Monday Barry Gardiner told the BBC that staying in the customs union, which manages the trade of goods within the EU, would be a "disaster," adding in an article for the Guardian that it was simply "not possible" to remain in the arrangement after Brexit.

Gardiner, who is a member of Corbyn's Brexit negotiation team, insisted that remaining in the customs union would prevent Britain from striking new trade deals around the world.

"As a transitional phase, a customs union agreement might be thought to have some merit. However, as an end point it is deeply unattractive," he wrote.

"It would preclude us from making our own independent trade agreements with our five largest export markets outside the EU (the US, China, Japan, Australia and the Gulf states)."

However, a spokesperson for Corbyn told Business Insider on Tuesday that Labour would in fact keep the option of remaining in the customs union after Brexit.

"We need to be flexible in our approach and not sweep options off the table," they said.

"As we spelled out in our election manifesto, Labour believes that the Brexit negotiations should put jobs and the economy first, with the priority of tariff-free access to the European single market.

"We want to see a new partnership with the EU that maintains the benefits of both the single market and the customs union."

Corbyn's position is in line with comments previously made by Brexit Secretary Keir Starmer, who last month urged Prime Minister Theresa May to keep customs union membership "on the table".

They also follow comments earlier this month by the Shadow Business Secretary Rebecca Long-Bailey, who described the aim of Labour’s Brexit policy as attempting to "have our cake and eat it" on the single market and customs union.

Corbyn has insisted that Labour must leave the single market after Brexit, but has so far not been clear on his position on the customs union.

What is the customs union? And why does it matter?

The customs union is a core EU institution. Its member states enjoy barrier-free trade with each other and charge the same tariff on imports from outside the EU. Basically, in practice, this means nations importing goods into the EU pay the same tariff regardless of which member states they are importing to. Brexiteers, however, argue that the customs union stifles Britain's ability to trade because its member states are prohibited from striking their own free trade deals with nations outside of the EU.

The Tory government has been criticised by the Liberal Democrats, Greens, SNP and many Labour MPs for seeking to pursue a "hard Brexit" based on wrenching Britain from the EU's core institutions: the single market and customs union. Critics claim a hard Brexit would cost Britain trade and jobs and inflict huge damage on the national economy.

Yet Gardiner's vision for Brexit is almost indistinguishable from that of hard Brexiteers of the Conservative Party in that it is based on terminating Britain's membership of these institutions. Labour MPs Chuka Umunna pointed out on Sunday that countries like Norway, Iceland and Lichtenstein are part of the single market despite not being EU member states, and said Turkey is "basically" part of the customs union despite not being an EU member state.

Corbyn ruled out keeping Britain in the single market over the weekend. "The single market is dependent on membership of the EU," Corbyn told the BBC's Andrew Marr.

"What we have said all along is that we want a tariff-free trade access to the European market and a partnership with Europe in the future.

"The two things are inextricably linked so the question then is the kind of trade relationship of the future and we have made it very clear we want a tariff-free trade access with the European market."