David Cameron has used a question by Tim Farron on the plight of child refugees in Lesbos to make a “cheap joke” about the Liberal Democrats, to loud cheers from the Tory benches.

Mr Farron, who became the party’s leader following Nick Clegg’s resignation, raised the crisis on the Greek island at today’s Prime Minister’s questions.

“Yesterday I visited the refugee camps on Lesbos and there I met families that were inspirational and desperate,” he said.

Migrants wait under outside the Moria registration camp on the Lesbos.

“Alongside the British charity workers I found there, I am frankly ashamed that we will not offer a home to a single one of those refugee families.

“So may I ask the Prime Minister this question: Will he agree with a Save the Children plea that we take as a country 3,000 vulnerable unaccompanied children in Europe, some who are as young as six?”

Mr Cameron responded by welcoming his opponent’s first question as Liberal Democrat leader, adding: “It’s good to see such a high turnout of his MPs.”

The quip was greeted by loud cheers and laughs from Conservative MPs, who had been heard shouting “who?” as Mr Farron stood to speak.

He appeared to take the joke in good humour, smiling as the Prime Minister launched into his answer.

Refugee crisis - in pictures Show all 27 1 /27 Refugee crisis - in pictures Refugee crisis - in pictures A child looks through the fence at the Moria detention camp for migrants and refugees at the island of Lesbos on May 24, 2016. AFP/Getty Images Refugee crisis - in pictures Ahmad Zarour, 32, from Syria, reacts after his rescue by MOAS (Migrant Offshore Aid Station) while attempting to reach the Greek island of Agathonisi, Dodecanese, southeastern Agean Sea Refugee crisis - in pictures Syrian migrants holding life vests gather onto a pebble beach in the Yesil liman district of Canakkale, northwestern Turkey, after being stopped by Turkish police in their attempt to reach the Greek island of Lesbos on 29 January 2016. Getty Images Refugee crisis - in pictures Refugees flash the 'V for victory' sign during a demonstration as they block the Greek-Macedonian border Refugee crisis - in pictures Migrants have been braving sub zero temperatures as they cross the border from Macedonia into Serbia. Refugee crisis - in pictures A sinking boat is seen behind a Turkish gendarme off the coast of Canakkale's Bademli district on January 30, 2016. At least 33 migrants drowned on January 30 when their boat sank in the Aegean Sea while trying to cross from Turkey to Greece. Getty Images Refugee crisis - in pictures A general view of a shelter for migrants inside a hangar of the former Tempelhof airport in Berlin, Germany Refugee crisis - in pictures Refugees protest behind a fence against restrictions limiting passage at the Greek-Macedonian border, near Gevgelija. Since last week, Macedonia has restricted passage to northern Europe to only Syrians, Iraqis and Afghans who are considered war refugees. All other nationalities are deemed economic migrants and told to turn back. Macedonia has finished building a fence on its frontier with Greece becoming the latest country in Europe to build a border barrier aimed at checking the flow of refugees Refugee crisis - in pictures A father and his child wait after being caught by Turkish gendarme on 27 January 2016 at Canakkale's Kucukkuyu district Refugee crisis - in pictures Migrants make hand signals as they arrive into the southern Spanish port of Malaga on 27 January, 2016 after an inflatable boat carrying 55 Africans, seven of them women and six chidren, was rescued by the Spanish coast guard off the Spanish coast. Refugee crisis - in pictures A refugee holds two children as dozens arrive on an overcrowded boat on the Greek island of Lesbos Refugee crisis - in pictures A child, covered by emergency blankets, reacts as she arrives, with other refugees and migrants, on the Greek island of Lesbos, At least five migrants including three children, died after four boats sank between Turkey and Greece, as rescue workers searched the sea for dozens more, the Greek coastguard said Refugee crisis - in pictures Migrants wait under outside the Moria registration camp on the Lesbos. Over 400,000 people have landed on Greek islands from neighbouring Turkey since the beginning of the year Refugee crisis - in pictures The bodies of Christian refugees are buried separately from Muslim refugees at the Agios Panteleimonas cemetery in Mytilene, Lesbos Refugee crisis - in pictures Macedonian police officers control a crowd of refugees as they prepare to enter a camp after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures A refugee tries to force the entry to a camp as Macedonian police officers control a crowd after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures Refugees are seen aboard a Turkish fishing boat as they arrive on the Greek island of Lesbos after crossing a part of the Aegean Sea from the Turkish coast to Lesbos Reuters Refugee crisis - in pictures An elderly woman sings a lullaby to baby on a beach after arriving with other refugees on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures A man collapses as refugees make land from an overloaded rubber dinghy after crossing the Aegean see from Turkey, at the island of Lesbos EPA Refugee crisis - in pictures A girl reacts as refugees arrive by boat on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures Refugees make a show of hands as they queue after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures People help a wheelchair user board a train with others, heading towards Serbia, at the transit camp for refugees near the southern Macedonian town of Gevgelija AP Refugee crisis - in pictures Refugees board a train, after crossing the Greek-Macedonian border, near Gevgelija. Macedonia is a key transit country in the Balkans migration route into the EU, with thousands of asylum seekers - many of them from Syria, Afghanistan, Iraq and Somalia - entering the country every day Getty Images Refugee crisis - in pictures An aerial picture shows the "New Jungle" refugee camp where some 3,500 people live while they attempt to enter Britain, near the port of Calais, northern France Getty Images Refugee crisis - in pictures A Syrian girl reacts as she helped by a volunteer upon her arrival from Turkey on the Greek island of Lesbos, after having crossed the Aegean Sea EPA Refugee crisis - in pictures Refugees arrive by boat on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures Beds ready for use for migrants and refugees are prepared at a processing center on January 27, 2016 in Passau, Germany. The flow of migrants arriving in Passau has dropped to between 500 and 1,000 per day, down significantly from last November, when in the same region up to 6,000 migrants were arriving daily.

Mr Cameron repeated his commitment to taking in 20,000 refugees directly from camps outside of Europe, claiming that 1,000 would be “housed, clothed and fed” in Britain before Christmas.

But he refused the plea made by Save the Children, saying he had examined it “very carefully” but that “there are other NGOs and experts who point to the very real danger of separating children from their broader families”.

Commentators on Twitter were quick to criticise Mr Cameron’s response to the Liberal Democrat leader’s question.

“Tim Farron asks a serious question about 3000 refugee children stranded in Lesbos and Mr Cameron makes a cheap joke about Lib Dem party,” Emma Litson wrote.

Tim Farron, the new Liberal Democrat leader, took the Prime Minster's joke in good humour (Getty)

Nick Barlow, a former Liberal Democrat councillor, wrote: “So, Tim Farron asks an important question about unaccompanied child refugees. Cameron’s first response is a joke. Stay classy, Dave.”

Another commenter dismissed Mr Cameron’s “snide and shabby answer”, while one criticised the Prime Minister’s “disgusting mocking”.

Kirsty McNeill, Save the Children’s director of campaigns, said iwas heartening that Mr Farron raised the issue of the thousands of unaccompanied children making desperate journeys to Europe alone, saying they were "incredibly vulnerable" to abuse by people traffickers and criminal gangs.

“Despite the Prime Minister’s comments, we are not talking about children who have extended family they can stay with – these are children who are alone with few safe places to stay and no one to protect them. We work tirelessly to allow children to remain in, or return to, the care of their families, but in some cases this simply isn’t possible," she added.

"That’s why we would like David Cameron to consider again taking in 3,000 unaccompanied children who are already in Europe alone and unsupported, which Save the Children has calculated is Britain’s fair share.”

Lesbos, which is roughly the size of Skye, has seen thousands of refugees and migrants arrive on its shores every day through the summer and the influx shows no sign of abating.

Refugees arriving on the Greek island of Lesbos on Wednesday (Getty Images)

Mr Farron was one of several politicians to visit the island, where families are sleeping rough or in squalid refugee camps as their asylum claims are processed, before they can continue their journey towards western Europe.

Save the Children is one of the charities working on Lesbos and at other points on refugees’ routes from Turkey and North Africa into Italy and Greece, and onwards to more affluent countries.

Last month, it drew up a proposal for the UK to take a “fair share” of the most vulnerable unaccompanied children from “frontline” countries receiving the highest number of arrivals in Europe.

“The response to this crisis at the European level is progressing at a painstakingly slow pace,” a spokesperson for Save the Children said, listing dangers including sexual abuse, violence, exploitation and trafficking.