New Zealand’s cabinet will meet on Monday morning to begin work to change gun laws, as the country continued to grapple with Friday’s attacks in Christchurch, which left at least 50 people dead.

Prime minster Jacinda Ardern said on Sunday that gun regulation would be discussed, telling reporters: “We cannot be deterred from the work we need to do on our gun laws in New Zealand. They need to change.”

Civilians in New Zealand own an estimated 1.2m firearms, making the country’s per capita rate of gun ownership higher than Australia’s, but still far below the US. It is alleged that the suspect in the attack, Australian Brenton Tarrant, had a firearms licence and five guns.

As tributes were paid to the victims, 34 people remained in hospital, including a four-year-old girl who is in a critical condition.

Facebook removed 1.5m videos of New Zealand terror attack in first 24 hours Read more

Ardern said the suspect had sent a “manifesto” her office minutes before the attacks. “I was one of more than 30 recipients of the manifesto that was mailed out nine minutes before the attack took place. It did not include a location, it did not include specific details,” she said. “I am advised that within two minutes of its receipt, at least my office it was conveyed directly to parliamentary security.”

The prime minster said that if the document had “provided details that could have been acted upon immediately it would have been”. “Unfortunately, there were no such details in that email,” she said.

She also said there were “questions to be answered” about the role social media played in disseminating video of the attack and confirmed she had been contacted by Sheryl Sandberg, Facebook’s chief operating officer, in the wake of the shootings.

New Zealand’s police commissioner Mike Bush addressed concerns that police took too long to respond to the massacre. He said officers were at the scene within six minutes of the first emergency call and apprehended the suspect within 36 minutes.

Bush said Tarrant remains the only person charged in relation to the attacks and he would likely face more charges. A woman apprehended at the scene was released without charge. Another 18-year-old man arrested in a vehicle has been charged with firearm offences unrelated to the terrorist attack.

The White House pushed back against any attempt to link Donald Trump to the accused gunman, saying the act of a disturbed individual cannot be blamed on any one politician. In the “manifesto” the suspect praised the US president as “a symbol of renewed white identity and common purpose” but said he did not support his policies. White House acting chief of staff Mick Mulvaney told Fox News Sunday: “The president is not a white supremacist ... I’m not sure how many times we have to say that.”

More details about Tarrant emerged on Sunday. Greek police said he had stayed on the Greek islands of Crete and Santorini and travelled through the country twice in 2016. Authorities in Bulgaria, Turkey, Croatia and Hungary have also confirmed visits by Tarrant between 2016 and 2018 as he apparently studied battles between Christians and the Ottoman Empire.

Bush said New Zealanders should return to their normal lives and routines on Monday, but they would see a visible police presence in Christchurch “on the streets, around your businesses, around your schools, and even in the air, right across the country. So you will feel safe to go about what you want to do.”

• Crisis support services can be reached 24 hours a day. In New Zealand, the crisis support service Lifeline can be reached on 0800 543 354. In Australia, Lifeline is 13 11 14. In the UK and Irish Republic, contact Samaritans on 116 123. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. Other international helplines can be found at www.befrienders.org.