Britain says it might seek to remain in a customs union with the European Union for a time to avoid border chaos after leaving the bloc.

The Department for Exiting the European Union said Tuesday that there could be "a temporary customs union between the UK and the EU". It also said a future "customs partnership" could eliminate the need for a customs border between Britain and the EU.

That would provide certainty for businesses, the government said, aiming to address a main concern of companies who fear the introduction of customs checks will cause expensive delays. 

The question of whether there will be economic barriers with the EU after Brexit in March 2019 has been the subject of mixed signals from UK government ministers.

The single market between the UK and the EU can ensure tariff-less trade in goods and services and is linked closely by the EU with other rights, such as the right of EU citizens to cross borders. The customs union allows goods to move within the EU without checks, but also imposes tariffs on imports from outside the EU, which would prevent Britain striking new free trade deals while it remains inside the arrangement.

The British proposal says the UK should be free to negotiate new trade relationships during the transition period, something EU officials are likely to find problematic. 

The EU said it took note of Britain's suggestions, "but we will only address them once we have made sufficient progress on the terms of the orderly withdrawal" from the bloc. 

The EU wants to make progress on several key issues by October, including the financial bill for Britain's exit, but Brexit minister David Davis told media that there would not be an agreed figure on the financial settlement by then. "We're going to talk it through very, very carefully, so at this stage we're not going to commit," he said.

The customs union document is the first of a series of papers to be published by the UK government on key negotiation issues.