The US has charged Hamas leader Yahya Sinwar and several other top figures in the Palestinian group in connection with its deadly attack on Israel on 7 October last year.

The justice department said it was indicting six Hamas members with crimes including the murder of US citizens, conspiracy to finance terrorism and use of weapons of mass destruction.

US Attorney General Merrick Garland said Hamas had “perpetrated the deadliest massacre of Jews since the Holocaust” during its assault last year in southern Israel.

It is the first step by US law enforcement to hold accountable the ringleaders of the assault, though up to three of those named in the indictment are dead and Sinwar is believed to be hiding in tunnels somewhere under Gaza.

In a video statement, Mr Garland said the group were responsible for “financing and directing a decades long campaign to murder American citizens and endanger the security of the United States”.

The group also “led Hamas’s efforts to destroy the state of Israel and murder civilians in support of that aim”.

He noted the 7 October attack on Israel by Hamas, in which the group “murdered entire families”.

“They murdered the elderly and they murdered young children. They weaponised sexual violence against women.”

He added that during the attack the group “murdered over 1,200 people” and “perpetrated the deadliest massacre of Jews since the Holocaust”.

Other Hamas leaders charged include former leader Ismail Haniyeh, Marwan Issa, the deputy leader of the organisation’s armed wing; Khaled Mashaal, who leads the group outside Gaza and the West Bank; Mohammed Deif and Ali Baraka.

The charges also include conspiracy to bomb a place of public use resulting in death, conspiracy to finance terrorism and material support for acts of terrorism resulting in death.

The justice department’s complaint notes that all the “defendants are either deceased or remain at large”.

Haniyeh, Issa and Deif have all been killed in Israeli attacks in the past year, according to reports.

The attorney general referred in his remarks to the killing last week of American-Israeli hostage Hersh Goldberg-Polin, 23, in addition to 40 other American citizens killed in the 7 October attack and eight taken hostage.

“We are investigating Hersh’s murder, and each and every one of Hamas’ brutal murders of Americans, as an act of terrorism,” he said.

FBI Director Christopher Wray added that Hamas is classified in the US as a foreign terrorist organisation “with a long history of violence, and the group’s actions have resulted in increased terrorism threats in the US and against American interests throughout the world”.

US officials also noted the role that Iran plays in supporting Hamas.

“Hamas’ attacks have played a significant role in the Government of Iran’s regional and global campaign of supporting terrorism to weaken and ultimately destroy both the United States and Israel,” the justice department’s statement alleges.

If convicted, the group faces a maximum penalty of life in prison or a death sentence.

The charges had been filed in February but were kept under seal until Tuesday in case the US had the opportunity to arrest any of the accused, an unnamed justice department official told CBS News, the BBC’s US partner.

“Following Haniyeh’s death and recent developments in the region, it was no longer necessary to keep those charges under seal,” the official said.

Over the weekend, President Joe Biden condemned the Hamas killing of Goldberg-Polin, calling it “as tragic as it is reprehensible.”

“Make no mistake, Hamas leaders will pay for these crimes,” Mr Biden said.

Meanwhile, the UK has defended its decision to ban some weapons sales to Israel over concerns about how they might be used in Gaza.

Hamas attacked southern Israel on 7 October, killing about 1,200 people and taking another 251 hostage.

More than 40,000 people have been killed in Gaza since then in Israel’s ongoing military campaign, according to the territory’s Hamas-run health ministry.