Britain was sidelined from talks about the refugee crisis this week after Theresa May was excluded from a major summit hosted by French President Emmanuel Macron.

Amid growing concerns about Britain’s waning influence abroad, Downing Street confirmed Theresa May was not invited to the Paris summit attended by Mr Macron and German Chancellor Angela Merkel, as well as Spanish Prime Minister Mariano Rajoy and Italian Prime Minister Paolo Gentiloni.

The meeting, which was also attended by leaders from Libya, Chad and Niger, was aimed at addressing the progress of refugees and migrants through the so-called “western Mediterranean route” to Europe – which sees tens of thousands of people travelling from Africa every year, some to Britain.

The Government says the lack of an invite for Ms May was justified because Britain is leaving the EU; however, the policies agreed at the meeting are likely to be relevant to the UK.

Some migrants who travel the western Mediterranean route from Africa end up trying to reach the UK and the largest group of migrants in the Calais “jungle” camp is fleeing Sudan – a country at the end of the route.

Jo Swinson, Lib Dem foreign affairs spokesperson and deputy leader told The Independent the lack of an invitation for Ms May showed that Britain was gradually seeing its influence in world affairs wane to that of a “rocky outcrop off the shores of Northern Europe”.

“It is becoming increasingly clear that Theresa May is leading Britain into decline,” she said.

“The UK is seen to have closed its door to the rest of the world, under this Government we face a marginalised future on the fringes of the world stage.

Refugee child receiving rations in Greece (Getty) (Getty Images)

“Theresa May should see the lack of a UK invite to this summit as a wake-up call, we need to stay in the single market, stay in the customs union and continue to play a role in world affairs. Instead she is letting us become no more than a rocky outcrop off the shores of Northern Europe.”

A Brussels-based official said: “We are just not being taken seriously at the moment.”

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Leaders at the summit agreed an action plan to boost border controls and coastguard patrols in the African countries that attended the summit. A scheme to process asylum applications in Africa was also brought forward.