Attacks on refugee accommodation have doubled in Austria, seeing homes firebombed, vandals spray Nazi graffiti on walls and a man threaten to “get a gun and shoot the dogs”.

The interior ministry revealed the figures at the request of an MP, who said the vast majority of cases were motivated by hatred and called for more to be done to catch the culprits.

Albert Steinhauser, an opposition Green party politician, said he was dismayed to find out that more than three quarters of the 49 recorded cases remain unsolved.

“The most important thing is for the interior ministry to take these incidents seriously and make every necessary effort to investigate,” he told the Austria Press Agency.

Among the incidents was a firebombing that saw two Molotov cocktails launched at a refugee home in Himberg, Lower Austria, in November.

It was one of several reported arsons, including a fire in Rohrbach, Upper Austria, in June, which damaged one accommodation centre so badly it had to be evacuated and rebuilt.

Police said refugees were put at severe risk in August when assailants broke into a storage unit and cut a gas supply hose “to cause a leak” that went unnoticed for more than a week.

Authorities said the motivations of the perpetrators were unknown, but they could have caused poisoning or a gas explosion.

In May, a man approached a centre in the Alpine town of Imst and shouted threats at asylum seekers, saying he would “get a gun and shoot the dogs”. He was later arrested.

The following month, a man falsely posing as a police officer entered a home in Fulpmes armed with a baton to carry out a supposed “inspection”.

Other attacks involved fireworks, paintball guns and homemade Molotov cocktails, while others saw stones and other projectiles launched at windows.

Most incidents involved vandalism, including the smashing of windows and spraying of racist and Nazi graffiti, including swastikas, the phrase “Heil Hitler” and SS runes.

Activists believe many more incidents may have occurred in 2016 than the 49 officially recorded, compared to 25 in 2015.

The interior ministry also listed numerous attacks and threats by asylum seekers, including carers being threatened with “decapitation” gestures in Linz, where another refugee told his supervisor “I will kill you all”.

Austrian citizens and asylum seekers march during a pro-refugee protest called 'Let them stay' in Vienna, Austria on November 26, 2016. (AFP/Getty Images)

At least two sexual assaults were recorded. In one attack in Bad Hall in June, a female supervisor was threatened with a smashed glass, pinned to a wall by the neck and assaulted until she managed to flee.

A female worker was repeatedly assaulted by a migrant in Poysdorf, attempting to kiss her, grabbing her breasts and leaving her with a bleeding lip on one occasion.

A female social worker was forcibly held in her office and prevented from making phone calls by three Afghan asylum seekers in Görtschach, who told police they terrorised her for five hours “because she was a woman and a ‘bitch’”.

“We have to look closely at what the causes are. We strongly suspect that trauma, experiences of war and extreme violence play a role,” Mr Steinhauser said, calling for better psychiatric care.

In all but two of 49 violent incidents or threats against workers recorded at refugee homes the perpetrators were caught, the interior ministry said.

More than 130,000 people have applied for asylum in Austria since the start of the refugee crisis, with the country sitting on the route from the Greek islands into western Europe.

In neighbouring Germany, more than 900 attacks on refugee homes were recorded in 2016, with the arrival of more than one million asylum seekers driving a spike in political violence and hate speech.

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. 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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.

Austria, where the far-right Freedom Party (FPÖ) has seats in Parliament and almost had its leader elected President last year, has been hardening its stance towards refugees this year.

The government is doubling the amount of money offered to asylum seekers who leave the country voluntarily, while announcing plans to increase surveillance, ban the burqa and force refugees to sign an “integration contract” and work for benefits.

Christian Kern, the Austrian Chancellor, announced he would be seeking an exception from accepting more asylum seekers under EU quotas.

He argued that Austria had fulfilled its obligation and taken in its “fair share”, sending a letter to kick-start negotiations with the European Commission on Tuesday.

Fewer than 14,500 migrants have been relocated from overcrowded camps in Greece and Italy under a two-year plan that was supposed to see 160,000 people housed by September.

Thousands of refugees continue to make treacherous sea crossings to Europe, with more dying than ever before on the passage between North Africa and Italy.