German Chancellor Angela Merkel on Tuesday expressed horror at a near-fatal knife attack against a town mayor, apparently motivated by his pro-refugee stance and which left him with a six-inch neck wound.

Andreas Hollstein, 54, mayor of the western town of Altena, was stabbed late Monday at a kebab shop by a man who had loudly criticised his liberal refugee policy.

Hollstein said that without two shop employees who rushed to help him, he would "probably not be here today".

With a large bandage on his neck and a wavering voice, Hollstein told reporters that the attacker, a 56-year-old German, had asked him if he was the mayor before pulling the knife and then said: "You let me die of thirst and take in 200 refugees in Altena."

Merkel, who has faced a strong backlash over her welcoming stance toward refugees, was "horrified" by the attack on Hollstein and "very relieved that he was already able to return to his family," her spokesman Steffen Seibert tweeted. "Thanks also to those who helped him."

Hollstein, a member of Merkel's Christian Democrats (CDU), said he believed that "a coarsening of the public debate about refugees" had led to the assault.

"I even received emails today approving of the attack -- that says something about the state of our country," he said, adding that he and his family had received repeated threats in recent years.

Hollstein said the attacker had been drinking but was by no means incapacitated, noting it had taken three men to overpower him.

The suspect, identified only as Werner S., was arrested at the scene while Hollstein was taken to a local hospital for treatment and released hours later, police said in a statement, referring to an "apparent xenophobic motive".

Prosecutors said the alleged assailant had a history of "psychological problems" but no known ties to far-right groups, a spokesman told reporters.

He is facing a charge of attempted murder.

- 'Like a good mayor should' -

The kebab shop owner, Demir Abdullah, who came to Hollstein's aid along with his son, who was also injured in the attack, confirmed that Hollstein was targeted specifically.

"He asked 'Are you the mayor?'... then he reached for his knife and stabbed him in the neck," Abdullah told German television.

The town of about 17,000 people was well known for taking in a larger share of asylum seekers than legally required amid the mass influx that has brought more than one million migrants and refugees to Germany since 2015.

Hollstein, who accepted a national award from Merkel in May for the town's work with refugees, said that Altena had welcomed about 450 people and that he had no plans to reverse his stance.

"I'm going to continue to work for refugees, for those who are already here and for those who are still arriving, for the weak and the strong in our society, like a good mayor should," he said.

Justice Minister Heiko Maas posted on Twitter that "we must never accept that people are attacked because they help others," adding that there was no space "for hate and violence" in Germany.

The assault revived memories of a knife attack on Cologne's mayor Henriette Reker in October 2015 by a rightwing extremist angered by her liberal position on refugees.

The attempt on her life came on the eve of a local election and at the height of the influx to Germany, where sentiment is still deeply divided on the country's humanitarian responsibilities and its ability to integrate newcomers.

While most mainstream parties back the principle of Germany taking in people fleeing war zones such as Syria, the backlash led the far-right Alternative for Germany (AfD) party to win its first seats in parliament in September's general election.

Although Merkel won a fourth term in the poll, the AfD's presence has severely complicated her efforts to cobble together a ruling coalition.

The AfD scored nearly 12 percent of the vote in Altena's electoral district, just below the 13 percent it drew nationally.