This article was originally published in The Guardian after a collaborative investigation. Read the full news stories in The Guardian (English) and Altinget (Danish) and our in-depth explanation of the investigation.

Denmark’s defence ministry said it would launch a review after evidence emerged showing its air force participated in airstrikes on Libya that killed 14 civilians in 2011, the first time any of the 10 countries involved in the Nato bombing campaign has acknowledged a possible link to non-combatant casualties.

Documents released under freedom of information show the Danish air force had concluded privately as long ago as 2012 that two F-16 attacks were connected to civilian casualty reports compiled by the UN, media and human rights groups.

However, this acknowledgment was not made public at the time, effectively preventing a relative of the Libyans killed from seeking compensation or redress, because he did not know which country may have been behind the bombing.

Nato attacks involving Danish fighter jets in which non-combatants were killed include:

• an airstrike on Surman, nearly 40 miles west of Tripoli, on 20 June 2011 that killed 13 civilians, including five children and six members of one family. A surviving family member says the target was only a residential compound, owned by a retired Libyan government member, but Nato said at the time it was “a legitimate military target” despite reports of non-combatant deaths;

• the bombing of an apartment block in Sirte, central Libya, on Sept 16 2011 that killed two, a man and a woman who was five months pregnant. Although there were unconfirmed reports of snipers on the rooftop, questions were raised in the aftermath whether an attack would have been proportionate, given civilians were killed.

The Danish defence ministry said in a statement that while the events took place many years ago, it had begun a review. “The Minister of Defence has requested the Defence Command to assess whether the documents in question indicate that there were ramifications of such magnitude that an investigation should have been conducted at that time within the coalition or Nato framework,” it added.

One newly released document, written in English, and sent in May 2012 from Danish military command to the country’s Nato representatives, said that “Danish aircraft participated in a number of the specific attacks” listed as having caused civilian casualties by investigators from the UN International Commission of Inquiry on Libya, Human Rights Watch and the New York Times.

“Civilian casualties during the conduct of these attacks cannot be ruled out,” the Danish internal review, previously marked secret, concluded.

The Danish admission of a link with the deadly airstrikes follows a joint investigation between Altinget, a Danish news site, Airwars, a civilian harm watchdog, and the Guardian.

The full article in The Guardian can be read here.