The European Union must prepare for the possibility that talks for a deal with the UK over their future relationship could fail, German Chancellor Angela Merkel has said.

"I will keep pushing for a good solution, but the EU and Germany too must and should prepare for the case that an agreement is not reached," Mrs Merkel told the Bundestag.

She made her comments as Germany, Europe's biggest economy, takes over the presidency of the 27-member bloc.

The UK officially completed its delayed departure from the European integration project on 31 January.

London and Brussels now have until the end of December to strike a brand new agreement or end their half-century relationship without specific plans for how they intend to trade or coexist in other fields.

Without a new agreement, they would see ties reduced to minimum standards set by the World Trade Organisation with high tariffs and serious disruptions to business.

After several months of disruption by the coronavirus pandemic, the EU and the UK launched on Monday an intense five weeks of negotiations on a deal to define their post-Brexit relations, with London keen to wrap things up quickly.

With both sides still entrenched in their positions, Prime Minister Boris Johnson had insisted that Britain was ready to accept the consequences of no deal if common ground cannot be found.

Mrs Merkel has also sharpened her tone, questioning in an interview if London really wanted a deal.

A deal would have to be done by the autumn to give national parliaments as well as the EU parliament enough time to ratify the agreement.