Henriette Reker, who is running for mayor of the city of Cologne as an independent, and one of her aides were left severely injured after being stabbed

A German mayoral candidate has been stabbed in the neck in an attack with 'anti-foreigner motives'.

Henriette Reker, who is running for mayor of the city of Cologne as an independent, and one of her female aides were left severely injured in the savage assault.

Police believe that she was targeted because of her extensive work in housing Germany's refugees.

Germany’s interior minister said the attack underlined growing concerns over hatred and violence during the refugee crisis.

German leader Angela Merkel expressed her 'shock' following news of the attack.

Ms Reker, 58, currently heads Cologne’s social affairs and integration department and is responsible for refugee housing.

A 44-year-old man sprang on the pair while they were campaigning in the western city, the fourth largest in Germany, police said.

The German national and resident of Cologne said he had been unemployed for several years.

He told officials that he targeted Ms Reker and that ‘he wanted to and did commit this act because of anti-foreigner motives’, according to Norbert Wagner, head of the police criminal investigation unit in Cologne.

Three other people were also injured, although not seriously.

Interior Minister Thomas de Maiziere described the stabbing as ‘an attack on our democracy’ and said he had long been ‘concerned by the hate-filled language and violent actions that accompany the refugee debate in Germany’.

‘This cowardly attack in Cologne is further evidence of the increasing radicalisation of the refugee debate,’ he continued.

A 44-year-old man sprang on the pair while they were campaigning in the western German city, police said

Cologne Police Chief Wolfgang Albers said Ms Reker has been involved in the supporting and helping to house refugees in the city

Chancellor Angela Merkal, Germany's leader, has expressed 'shock' at the news of the attack. Ms Merkel’s policy has led to growing tensions in Germany, triggering a backlash from her conservative allies and spawning a growing number of increasingly vocal far-right protests

Mr Wagner described the attack on Reker as ‘targeted and deliberate’.

‘In his plea, he said that he committed this act out of xenophobic motivation,’ Wagner continued.

‘From our initial investigations, we have ascertained that he probably acted alone. So far, we have no knowledge of other people taking part in this sad act.’

Cologne Police Chief Wolfgang Albers said Ms Reker 'is stable, but not out of the woods yet'.

Germany, a top destination for migrants, expects to receive up to a million new arrivals this year. But many Germans feel that the country cannot cope with the record numbers of refugees.

Police said the attack stabbed Ms Reker and her aide at around 9am (7am GMT) at an information stand for Chancellor Angela Merkel’s party, the Christian Democrats (CDU).

The other three people were injured immediately afterwards.

Eyewitnesses said that the attacker headed straight for Ms Reker.

Ms Reker is loaded into an ambulance before being rushed to hospital, after being seriously injured in the attack

Cologne Police Chief said that Ms Reker is now stable, but 'is not out of the woods yet' following the assault

‘She had arrived here just a few minutes before,’ said Bernd Petelkau, a local CDU official. ‘She was talking to two other party members when it happened.’

Ms Reker is running as an independent but is backed by Ms Merkel’s conservatives and two other parties.

Prosecutor Ulf Willuhn said officials will now investigate whether that was in fact the man’s primary motive or whether his health played a role.

They plan to carry out a psychiatric examination.

When asked whether the suspect had specifically mentioned Ms Reker’s or Ms Merkel’s policies on refugees, Mr Wagner said: ‘No. He made general statements in that direction – he didn’t mention Ms Merkel at all.’

Police guard the scene from intruders following the stabbing in Cologne. Ms Reker has been instrumental in organising accommodation for Germany's refugees

Germany, a top destination for migrants, expects to receive up to a million new arrivals this year. But many Germans feel that the country cannot cope with the record numbers of refugees

Cologne is due to hold elections for mayor on Sunday, which officials said will go ahead as planned following the attack.

Attacks on politicians are rare in Germany, but there have been prominent cases.

Then-Interior Minister Wolfgang Schaeuble was shot by a deranged man while campaigning in October 1990, an attack that left him using a wheelchair.

A few months earlier, a mentally-disturbed woman stabbed Oskar Lafontaine, then a prominent member of Germany’s main opposition party, while he was campaigning in Cologne.

The stabbing comes as Merkel prepares to travel to Istanbul on Sunday for talks on the crisis with Turkish President Recep Tayyip Erdogan, who has heaped scorn on Europe’s efforts to deal with the crisis so far.

The stabbing comes as Merkel prepares to travel to Istanbul on Sunday for talks on the crisis with Turkish President Recep Tayyip Erdogan, who has heaped scorn on Europe’s efforts to deal with the crisis so far

Ms Merkel has pushed for a fairer distribution of people across the European Union, but the crisis has sorely tested ties between member states and put unprecedented strain on the right to free movement that is at the core of the 28-nation bloc’s values

More than 630,000 people fleeing war and misery in the Middle East and Africa have landed on Europe’s shores this year, with many making risky sea crossings from Turkey to Greece

Ms Merkel has pushed for a fairer distribution of people across the European Union, but the crisis has sorely tested ties between member states and put unprecedented strain on the right to free movement that is at the core of the 28-nation bloc’s values.

Slovenia said on Saturday that it was drafting in the army to help police cope with an expected influx of thousands of migrants arriving after Hungary shut its border with Croatia overnight in its latest hardline move to stop the flow of people.

More than 630,000 people fleeing war and misery in the Middle East and Africa have landed on Europe’s shores this year, with many making risky sea crossings from Turkey to Greece.

Highlighting the human cost of the crisis, another 12 people drowned on Saturday when their wooden bank sank off the Turkish coast as they were trying to reach the Greek island of Lesbos.