Extremists imposing Islamic law in Mali’s north are abusing human rights, particularly those of women, and paying families for children to become rebel fighters, a senior U.N. official said on Wednesday after returning from the country.U.N. Assistant Secretary-General for Human Rights Ivan Simonovic said rebel fighters, including Islamist extremists allied to al Qaeda, in northern Mali were "buying loyalty” by abolishing taxes and paying for fighters and wives in a country where more than half the people live on less than $1.25 a day.Mali descended into chaos in March when soldiers toppled the president, leaving a power vacuum that enabled Tuareg rebels to seize two-thirds of the country. But Islamist extremists, some allied with al Qaeda, hijacked the revolt and then imposed harsh Islamic law in a desert region the size of France."During the first phase we had violations that were related to rebels taking control, they included summary execution of the captured soldiers, instances of lootings, of rapes,” he told reporters at the United Nations in New York."However, what is new now is that human rights violations are becoming more systematic, relating to the takeover of the radical Islamists,” he said. "They have now imposed an extremist version of sharia, so the population is suffering a number of human rights violations, particularly targeted at women.”Simonovic - who met with government officials, community leaders and displaced Malians during a recent visit - said the extremists had banned music and smoking and were forcing women to be covered and restricting their ability to work."It is frightening to hear lists are being compiled of women who are either pregnant or have children and are not married and we do not know what is going to happen to them,” he said.He said more forced marriages were happening - with a wife costing less than $1,000 - and that some men sometimes then sell the women again in what Simonovic described as "a smokescreen for enforced prostitution and rapes that are taking place.”