A prominent Palestinian prisoner has died in an Israeli jail after 86 days on hunger strike.

Khader Adnan was a senior figure in the militant group Islamic Jihad who Israel had charged with terrorism offences.

The Israel Prison Service said he had refused medical treatment before he was found unconscious in his cell on Tuesday.

Hours after his death, militants fired three rockets from the Gaza Strip towards Israel. No-one was hurt.

The Palestinian prime minister accused Israel of "deliberately assassinating" Adnan, while Islamic Jihad warned Israel that it would pay "the highest price".

Adnan, who was 44 and from the north of the occupied West Bank, had been in and out of detention by Israel over the past two decades.

He had been on hunger strike four times before in protest, helping to make his name well known to Palestinians.

It has become common for Palestinian prisoners to refuse food for extended periods while in Israeli jails, but in recent years such deaths have been rare due to medical intervention.

Adnan began a fifth hunger strike immediately after being detained by Israeli forces at his home in Arraba, near the city of Jenin, on 5 February.

Israeli authorities accused him of supporting terrorism, affiliation with a terrorist group and incitement, and he was due to go on trial this month.

But the Palestinian prisoners' rights group Addameer said he was being held on "spurious charges intended to further suppress Palestinian activists".

Last week, the Palestinian Prisoners' Club, another advocacy group, warned that Adnan's health situation was "very serious". It said he was being held in the clinic at Ramla prison in central Israel, and that he was refusing nutritional supplements and medical examinations.

Adnan's wife, Randa Mousa, said he was doing that because Israeli authorities had "refused to transfer him to a civilian hospital [and] refused to allow his lawyer a visit".

On Tuesday, the Israel Prison Service announced that Adnan was "found early this morning in his cell unconscious", and that was taken to a hospital where he was declared dead after efforts to revive him failed.

A senior Israeli official told AFP news agency that Adnan had risked his life by refusing medical attention, adding: "In recent days, the military appeal court decided against releasing him from detention solely on the merit of his medical condition."

However, Palestinian Authority Prime Minister Mohammed Shtayyeh said Israel had "carried out a deliberate assassination against the prisoner Khader Adnan by rejecting his request for his release, neglecting him medically, and keeping him in his cell despite the seriousness of his health condition."

Islamic Jihad, which is the second most powerful militant group in the Hamas-controlled Gaza Strip, said: "Our fight is continuing and the enemy will realise once again that its crimes will not pass without a response."

Randa Mousa said she did not want people to grieve her husband's death.

"We will only receive well-wishers, because this martyrdom is [like] a wedding, a [moment of] pride for us and a crown on our heads," she told journalists in Arraba, according to AFP.

She also insisted she did not want "a drop of blood to be shed" in retaliation.

"We don't want anyone to respond to the martyrdom. We don't want someone to launch rockets and then [Israel] strikes Gaza," she added.

There was no immediate claim for the three rockets that were fired from Gaza towards Israel soon after Adnan's death.

The Israeli military said the rockets set off sirens but that no interceptors were launched because they fell in open areas.

The fate of their prisoners in Israel is a top issue for Palestinians, who hold Israel responsible for their well-being.

There are some 4,900 Palestinians in Israeli prisons, according to Addameer.

Most are serving sentences after being convicted by Israeli courts or are being held for questioning, have been charged, or are awaiting or standing trial. It says another 1,016 are in "administrative detention", a controversial measure under which suspects are held indefinitely without charge or trial for renewable six-month periods. Palestinians regard all those held by Israel as political prisoners.

Addameer says the deportation of Palestinians from the occupied West Bank to prisons in Israel is illegal under international law. Palestinians also protest that it makes prison visits difficult because of strict conditions on Palestinians entering Israel from the West Bank.