German Chancellor Angela Merkel on Monday met with survivors and families of the 12 people who died in last year's attack on a Christmas market in Berlin.

"I know that some would have wanted such a meeting sooner," said Merkel ahead of the closed-door meeting, referencing a searing letter that some relatives penned earlier this month criticizing the chancellor for not reaching out.

"But it's important to me to make clear today how much our feelings are with the relatives and the injured. Nothing can make up for this complete change in people's lives, but still we will show sympathy and improve things where they need to be improved," she said.

On December 19, 2016, 24-year-old Anis Amri, a Tunisian national whose application for asylum had been rejected, hijacked a semi-trailer truck, killing Polish driver Lukasz Robert Urban.

A few hours later, Amri drove the truck into the Christmas market at Berlin's Breitscheidplatz, killing 11 people and injuring 56. He managed to escape and was shot dead by Italian police on December 23 after an altercation with officers outside Milan's Sesto San Giovanni train station.

Read more: Polish terror victim's parents disappointed with Germany

Authorities bungle intelligence

An ensuing investigation into the incident found that Amri had been deported from the European Union at least once before, and that he had been under surveillance by the authorities as a possible extremist. Police reportedly warned security services that Amri could be planning an attack.

In a letter published last week by German weekly Der Spiegel, relatives of the victims slammed officials for bungling the intelligence on Amri and treating them poorly.

"Almost a year after the attack, we note that you have not shared your condolences with us either in person or in writing," the letter said.

"In our opinion, this means that you are not living up to the responsibilities of your office."

'Very intensive talks'

At Monday's meeting, Merkel and other officials spent about three hours talking with about 80 victims and relatives from Germany, Israel, Italy, the Czech Republic and Ukraine.

Kurt Beck, the government's official representative for the victims, told the dpa news agency he was satisfied with the "very intensive talks."

"It was very good that the chancellor did this, which helped to relieve tension," he said. 

Beck released a government-commissioned report last week identifying a series of shortcomings in the response to the tragedy including: 

— Desperate relatives only being told three days after the attack that a family member had perished

— Relatives being sent "bills for autopsies — including warnings for late payment."

"Such experiences should never be repeated," he said, adding that Germany "was not prepared" to deal with the attack's aftermath.

Amri's mother willing to meet

Anis Amri's mother, Nour El Houda Hassani, told DW on Monday that she would be willing to meet with the mothers of her son's victims.

"As a mother who has lost her son, my pain increases every time I remember that he was responsible for the deaths of other mothers' children," she said.

Hassani added that her son had been "brainwashed" by terrorists, and that she would "never" reject a call for a meeting with victims' families.