British Prime Minister Theresa May has received heavy criticism for her refusal to condemn US President Donald Trump's ban on citizens of seven Muslim states.

May said the ban, which affects refugees, migrants, and visitors, was a "matter for the US" but later issued a statement that she disagreed with it.

The ban means a number of British citizens with dual nationality will not be allowed to enter the US, including Somalia-born Olympic gold medallist Mo Farah and Iraqi-born MP Nadhim Zahawi, a member of May's Conservative Party.

Citizens of Iran, Iraq, Libya, Somalia, Sudan, Syria, and Yemen are banned from entering the US, even if they hold permanent residency or valid visas.

I'm a British citizen & so proud to have been welcomed to this country. Sad to hear ill be banned from the USA based on my country of birth — Nadhim Zahawi (@nadhimzahawi) January 28, 2017

Leader of the opposition Labour Party, Jeremy Corbyn, said the government's lack of response was a "disgrace" and called for Donald Trump to be banned from the UK in response.

"[Trump] should not be welcomed to Britain while he abuses our shared values with shameful #MuslimBan and attacks on refugees and women." Corbyn wrote on his Twitter account.

"[May] would be failing the British people if she does not postpone the state visit and condemn Trump's actions in the clearest terms," he added.

@theresa_may hand in hand with the man who banned @Mo_Farah & Tory MP @nadhimzahawi. Yet she remains silent. pic.twitter.com/5BhkdWW2pL — Jeremy Corbyn MP (@jeremycorbyn) January 28, 2017

The opposition leader called on Britons to sign a parliamentary petition demanding that Trump be barred from the UK, which has picked up hundreds of thousands of signatures so far.

The response means parliament must consider debating a ban.

May met Trump at the White House on Friday, in a cordial meeting in which the pair held hands and promised stronger trade and security ties between their two countries.

The British prime minister used the meeting to invite Trump to visit the UK on a formal state visit.

Tim Farron, the leader of the Liberal Democrats, echoed calls for Trump to be banned, telling broadcaster Sky News that an invitation should "never have been made" .

Senior Scottish National Party politician Alex Salmond said May's conduct was a "shameful moment of cowardice" .

Despite stopping short of condemning May, Conservative MPs joined criticism of Trump's ban.

"President Trump's immigration and Syrian refugee ban is indefensible, unworkable and almost certainly unconstitutional," wrote Conservative MP James Cleverly on Twitter.

Trump's latest histrionic plan is nuts, unsustainable and counter-productive-all power to the courts and Congress to overturn it — Tim Loughton (@timloughton) January 29, 2017

British Foreign Secretary Boris Johnson said the country would defend the rights of British citizens abroad, in a tweet aimed at the US measures.

"We will protect the rights and freedoms of UK nationals home and abroad. Divisive and wrong to stigmatise because of nationality," he wrote.

Religious groups also condemned May's stance on Trump; the Muslim Council of Britain (MCB) said May should have used her time with the US president to remind him of the countries' shared values.

"In front of Mr Trump, the Prime Minister said that the point of the 'Special Relationship' was to have a frank dialogue. Well, this is one area where we need to be frank about where we stand," said Harun Khan, the MCB's secretary general.

#TheresaTheAppeaser is the one who approved the 'Go Home' vans, why people expect her to disagree with #MuslimBan? pic.twitter.com/Ec8PESVyMD — Tal Ofer (@TalOfer) January 29, 2017

Tal Ofer, of the Board of Deputies, the UK's leading Jewish organisation, said: "I wouldn't be surprised if the PM offered Trump her famous 'Go Home' vans" - a reference to May's deployment of trucks carrying banners telling migrants to leave the UK when she was home secretary.

"TheresaTheAppeaser"

Anger was also palpable on social media, with the hashtag TheresaTheAppeaser trending in the UK, as well as several related hashtags.

#TheresaTheAppeaser shows just how desperate the position for the UK is post Brexit. Willing to accept openly fascist policy for trade — Matthew Hexter (@hexter101) January 29, 2017

Many users compared May's behaviour to former British Prime Minister Neville Chamberlain's during the run-up to World War II.

Others said they were embarrassed at the deferential manner in which May had behaved towards Trump.

She did the equivalent of handing the car keys back to a drunk who intends to drive, saying ''it's up to him'' #TheresaTheAppeaser — Mrs Trellis (@theonlywayisup) January 29, 2017

Anti-Fascist groups have organised several protests against Trump, with one due to be held outside Downing Street Monday evening.