A video has shown a US Tomahawk missile hitting the Iranian naval base next to a primary school in Minab where more than 168 people, mostly children, were killed – adding to evidence that indicates the US was responsible for the school strike.

The video, released by the Iranian news agency Mehr and geolocated to the site by the investigative collective Bellingcat, shows the missile hitting the Minab compound on the morning of 28 February, when US-Israeli strikes on Iran began.

Combined with other evidence from the site, including videos verified by the Guardian, photos of the aftermath and satellite imagery of the strike, the new footage indicates that Shajareh Tayyebeh primary school was hit during a set of strikes by the US, as it targeted an adjacent Islamic Revolutionary Guards (IRGC) naval compound.

The strike demolished approximately half the school, killing scores of seven- to 12-year-old girls as they attended morning classes.

The evidence directly contradicts statements by the US president, Donald Trump, on Sunday that Iran was responsible for the school bombing. “In my opinion, based on what I’ve seen, that was done by Iran,” Trump said, without offering any evidence for his claim. “They’re very inaccurate, as you know, with their munitions. They have no accuracy whatsoever. It was done by Iran.”

Munitions experts say the missile shown in the video is clearly a Tomahawk, which is only used by the US in the current conflict.

“The video shows a Tomahawk missile striking a target. Given the belligerents, that indicates it is a US strike, as Israel is not known to possess Tomahawk missiles,” said NR Jenzen-Jones, the director of Armament Research Services, an intelligence consultancy that provides munitions analysis to governments and NGOs.

He added: “Despite various claims circulating online, the munition in question is clearly not an Iranian soumar missile [as] the soumar has a distinctive external engine located towards the rear, on the underside of the munition.”

Satellite imagery of the aftermath of the bombing shows that at least four buildings were hit in the strikes: the school, and three buildings in the IRGC compound.

While the primary school’s building was once part of the wider IRGC complex, it had been walled off from the IRGC compound for at least eight years, and had clear markers of being an educational building: its playing fields and colourful wall murals were visible in satellite images.

US military spokespeople have said they are “investigating” the strike. The school bombing has been described by Unesco as a “grave violation” of international law, and Human Rights Watch has called for it to be investigated as a war crime.