Media playback is unsupported on your device Media caption "Sweden, they took in large numbers," Donald Trump tells a crowd of supporters

During another ferocious attack on the media on Saturday evening, US President Donald Trump cited a non-existent incident in Sweden, baffling many - not least Swedes.

"You look at what's happening in Germany, you look at what's happening last night in Sweden. Sweden, who would believe this. Sweden. They took in large numbers. They're having problems like they never thought possible," the new US president told a crowd of supporters at a rally in Florida.

It was not entirely clear which incident he was referring to, as many on Twitter pointed out, including the former Swedish prime minister:

Some of those contacted the official @Sweden Twitter account - which is manned by a different Swedish citizen each week - to ask: "What happened in Sweden last night?" It was down to Emma, a school librarian, to allay concerns voiced from people around the world.

(Melfest is the music competition which selects Sweden's entry for the Eurovision Song Contest.)

"I went to bed at around 4am, then my daughter woke me up at 7am and in those four hours there were over 800 mentions...I usually get about a hundred," Emma told the BBC on Sunday, referring to the number of Twitter mentions the account received after President Trump's comments.

The hashtag #lastnightinSweden was soon trending on Twitter, and the Swedish embassy in Washington has asked the State Department for clarification.

Donald Trump's comments just weeks after one of his key advisers, Kellyanne Conway, cited a non-existent attack dubbed the "Bowling Green massacre".

So what exactly happened in Sweden on Friday?

There were no reported terrorist incidents in Sweden on Friday.

Sweden's Aftonbladet website helpfully summarised the day in news, which included:

A man setting himself on fire at a plaza in central Stockholm

Famous singer Owe Thornqvist suffering technical problems in rehearsals for the aforementioned Melfest

A man killed in workplace accident

Road closures in northern Sweden due to "harsh weather"

Police car chase through central Stockholm of a suspected drunk driver

Was he referring to something else?

Some people suggest Donald Trump might have been referring to a clip aired on Fox News on Friday night of a documentary about alleged violence committed by refugees in Sweden.

"There was an absolute surge in both gun violence and rape in Sweden once they began this open-door policy," Ami Horowitz, who made the documentary, told Fox News, referring to Sweden's decision to open its doors to large numbers of refugees in 2013.

Fox News is known to be among Donald Trump's favourite cable TV channels.

Others are speculating that the president may have confused Sweden with Sehwan, in Pakistan, where a suicide bombing on a Sufi shrine killed at least 80 people on Friday.

What is Sweden's refugee policy?

Sweden, with a population of about 9.5m, has taken in nearly 200,000 refugees and migrants in recent years - more per capita than any other European country.

It saw a sharp increase in asylum seekers in 2015, with more than 160,000 people arriving. With the influx, tensions also rose with some isolated attacks on immigrants, as well as pro- and anti-migrant demonstrations.

The killing of a 22-year-old woman in January 2016 by an asylum seeker based at the centre where she worked put further pressure on the government to reassess its approach to refugees.

There was a drop in numbers last year after the country introduced new border checks incurring longer processing times, as well as financial incentives for migrants who voluntarily returned to their country of origin.

Migrant crisis dominates Sweden's politics

How safe is Sweden?

Sweden has generally low crime rates.

Preliminary statistics from the Swedish Crime Survey (in Swedish) show only a marginal increase in 2016 from the year before. Fraud and crimes against individuals were up, but drugs crimes and theft had decreased.

The number of reported rapes increased by 13%, although that is still lower than the number reported in 2014 (6,700), as Sweden's The Local reports.

What about terror attacks?

There have been no terror attacks in Sweden since the country's open-door policy on migration began in 2013.

As British historian Simon Schama, says: "The real Swedish message: 200,000 refugees, no terrorist attacks."

In 2010, two bombs detonated in central Stockholm, killing the attacker - an Iraq-born Swedish man - and injuring two others, in what police described as a terrorist attack.

In October 2015, a masked man who was believed to have far-right sympathies killed a teacher and pupil in a sword attack.

And in Malmo last October, a fire at a Muslim community centre was claimed by the Islamic State group - the incident was cited by the White House in the list of incidents it deemed 'under-reported' by the media.

Separately, Sweden is believed to have the highest number of Islamic State fighters per capita in Europe. About 140 of the 300 who went to Syria and Iraq have since returned, leaving the authorities to grapple with how best to reintegrate them into society.

How Sweden became an exporter of jihad