Islamic State militants use sledgehammers on a toppled statue in a museum at a location said to be Mosul in this image taken from an undated video. Credit:Reuters Abu Mohammad al-Lahibi, who runs a clothing store in Mosul, said he had seen the militants gathering several hundred residents in front of the government building in Mosul to witness the execution. The couple were handcuffed and the woman was wearing a niqab, or full face veil. "Twelve [IS] militants were standing there who had bags with them filled with stones, and they began throwing the stones at them, and after the third stone the woman was killed," Mr Lahibi said. The man died a short while later, he said. Another witness said he tried to record video of the execution on his mobile phone but was ordered by the militants not to do so.

Iraqi pro-government fighters celebrate as they advance into Tikrit, 160 kilometres north of Baghdad, during a military operation to regain the city from Islamic State militants. Credit:AFP "I was moved by the crying of this woman, who started bleeding and then died from the stoning," said the witness, Saad, who gave only his first name out of concern for his safety. "I was standing there helpless. The government have left us as captives in the hands of [IS], who make all kinds of crimes in the city. The more I see their crimes, the more I hate them and realise they have come to carry out a paid agenda to destroy the city and its history and civilisation and to defame the image of Islam." The stoning was confirmed by an Iraqi military officer, Colonel Ahmed al-Jiboori, who is stationed at the Nineveh Liberation Camp east of Mosul. Colonel Jiboori also said that Kurdish peshmerga fighters in the area stopped an Islamic State attack east of the city, on Bashiqa Mountain, on Tuesday, killing 11 of the militants. Local residents said there had been more than a dozen executions by stoning since the militants began the practice in Mosul in August. The three men who were beheaded Tuesday were described by witnesses as in their late 20s. After a rumour got out that their uncle had met with the Kurdish leader Massoud Barzani, IS militants came to the uncle's home and took the three young men to a public street where they were beheaded.

Such attacks have led some Mosul residents to express urgency for an Iraqi government campaign to retake the city. But the progress of a pro-government offensive against IS has been slow, with the main force stuck around the city of Tikrit, south of Mosul, for four weeks. The government had announced last week that it was on the verge of capturing Tikrit from the militants but more recently said it was consolidating its forces around the city to minimise casualties, as the militants hold out in the center. Some 30,000 Iraqi troops and Shiite-dominated militias were involved in the effort against militants in Tikrit, who are believed to number in the hundreds or low thousands. On March 12, Iraqi officials announced that they were within days of completely subduing Tikrit and were doing so without help from the US-led coalition. When that did not happen, however, some said the lack of coalition air strikes was to blame. Lieutenant General Abdul-Wahab al-Saadi, the Iraqi military commander in Salaheddin province, said that he had requested coalition airstrikes but that they had not come. Earlier, US officials had said that Iraqi officials had not requested help. On Sunday, Hadi al-Amiri, the head of the Shiite militia known as the Badr Organisation, reacted contemptuously to such concerns. "Some of the weaklings in the army say that we need the Americans, but we say we do not need the Americans," he said.

"We are taking the necessary steps to protect our forces, and the tribes will hold the ground after we liberate the territory," he said on Iraqi television, explaining the delay in subduing Tikrit. New York Times