Bangladesh\'s Supreme Court on Tuesday sentenced a senior Islamist leader to death for mass murder, toughening a punishment originally handed down by the country\'s war crimes tribunal and sparking fresh violence. Abdul Quader Molla, 65, the fourth-highest leader of the Jamaat-e-Islami party, was given a life sentence in February by Bangladesh\'s International Crimes Tribunal. The tribunal has since January convicted six Islamists of crimes related to the 1971 war, in which pro-independence fighters battled Pakistani forces which were helped by local Islamist leaders. Molla\'s life sentence had sparked deadly protests and widespread riots and there was fresh unrest Tuesday in the southeastern port city of Chittagong after he was sentenced to hang. \"There were about 2,000 Jamaat protesters. They rioted, torching a police van and a private car,\" police chief Mohammad Mohiuddin told AFP, adding police fired rubber bullets and tear gas to disperse demonstrators. There were also clashes in the capital Dhaka and other cities and towns, police said. Outside the northern city of Bogra, a policeman was hurt when protesters hurled small bombs, police inspector Fazlul Karim told AFP. Molla was convicted of rape, murder and mass murder including the killing of over 350 unarmed Bengali civilians, a poet and a top journalist during the war, when he was a physics student at Dhaka University. Prosecutors described him as the \"Butcher of Mirpur\", a Dhaka suburb where he committed most of the atrocities. The war led to the creation of Bangladesh from what was then East Pakistan. Defence lawyer Tajul Islam said: \"We are stunned by the verdict. This is the first time in South Asian judicial history that a trial court sentence has been enhanced by a Supreme Court.\" Islam said the defence would seek a review of the verdict. But the law minister and the attorney general said there was no scope for review of the ruling. The prosecution said Molla could be executed by year-end unless he obtains a presidential pardon. The sentence drew strong criticism from the International Commission of Jurists, which called it \"incompatible with international principles of fair trial\". Jamaat, whose top leaders are either detained or being tried for war crimes, called a 48-hour nationwide strike to protest the verdict, calling it \"detrimental to justice\". The key opposition party has accused the secular government of trying to execute its entire leadership, three of whom have been sentenced to death by the war crimes court. A dozen other leaders are being tried. The government maintains the trials are needed to heal the conflict\'s wounds. Bangladesh has struggled to come to terms with its violent birth. The government says three million people died during the war while independent estimates put the death toll at 300,000 to 500,000. Molla\'s original life sentence triggered protests from Islamists as well as from secular activists who considered it too lenient. Tens of thousands of secularists massed at a square in Dhaka for weeks afterwards, demanding his execution. The protests forced parliament to change the law governing war crimes prosecutions, allowing prosecutors to appeal against the verdict and seek the death penalty in the Supreme Court. Hundreds of secular protesters cheered Tuesday as news of the latest verdict reached the capital\'s Shahbagh Square where they had massed since dawn. The judgement \"reflects the victory of the people who spent months on the roads to seek justice\" for the war crimes, said Imran Sarkar, who led the secular protest seeking death for Molla. The latest verdict could further inflame tensions just months before elections. The main opposition party, an ally of Jamaat, leads in opinion polls. In August, the High Court declared the registration of Jamaat-e-Islami illegal, banning it from contesting the elections due in January.