A team of lawyers in Sweden is seeking to gather evidence that could see Yemen’s ousted president and others face trial in the northern European country.

The Centre for European-Yemeni Relations, a group of Yemenis living in Europe, says it is collecting testimonies from people in hopes of proving that Ali Abdullah Saleh violated international law.

The case could be launched in accordance with a new Swedish law brought into force last year that allows the country to pursue charges against individuals accused of committing crimes against humanity, regardless of their nationality or where the alleged crimes took place, according to a report in Al Jazeera Arabic.

Also included in the Swedish investigation are Houthi leader Abdel Malik al-Houthi and Saleh’s son, who served as Yemen’s ambassador to the UAE after his father was deposed from his position as president in 2012, as well as leading members of Saleh’s former government.

News of the legal proceedings in Sweden come hours after Yemen saw its deadliest day of bombing since the beginning of Saudi-led airstrikes against Houthi fighters in late March.

Residents said that strikes on Wednesday killed at least 80 people in one day, with some estimating that the final death toll could be much higher.

At least 40 people were killed in the northern province of Hajjah, according to local residents, who said that the majority of those killed were civilians.

They also said at least 100 people were injured when the airstrike hit the district of Bakil al-Mir close to Yemen’s fortified border with Saudi Arabia.

The intended target of the airstrike remains unclear, although the area lies on the frontier of the mountainous border province of Saada where the Houthis maintain their stronghold.

Further south in the capital Sanaa, fighter jets targeted a special security headquarters in the centre of the city.

The military base, which is home to weapons depots and training facilities, was targeted over the course of several hours, with residents telling local news site al-Yemeny al-Gadeed that the bombing continued until 01:00 local time (22:00 GMT).

Hundreds of people are said to have been present at the site when the strikes began, as people queued to receive their wages on payday.

Around 40 people are said to have died in the series of strikes. A soldier who survived the attacks told Reuters that he could not be certain of the final death toll.

Wednesday’s bombings at the base marked the first time the site had been targeted during the two-month long campaign of airstrikes backed up by shelling from the sea off Yemen’s southern coast.

A prominent Yemeni photographer and artist who lives next to the headquarters said her house had been destroyed in the strikes.

Bushra al-Fusail, who has been behind several anti-war art projects since the bombing began on 26 March, said she had feared throughout the war that the site would be targeted.