LONDON (AFP) - US pop megastar Madonna and her British film director husband Guy Ritchie are to divorce, a newspaper reported on Wednesday, saying an announcement was imminent. After months of media speculation about strains in the eight-year marriage, Britain's Sun tabloid cited a "highly-placed source" as saying the split was being pushed for by 40-year-old Ritchie. "It's very sad. They were a great couple and brilliant parents. They just couldn't live together any more," said the unidentified source, adding that they "can't bear to live with the pretence any longer." Madonna's spokeswoman Barbara Charone told AFP: "We're not going to know anything until the US wakes up", adding that she was not even clear if there would be an announcement at that stage. Madonna, who is in the middle of her "Sticky and Sweet" world tour, married Ritchie in December 2000 in a lavish ceremony at a Scottish castle after meeting at a dinner party given by British rock star Sting. The couple have an eight-year-old son, Rocco, and a two-year-old son adopted in Malawi, David Banda. Madonna also has a daughter, 12-year-old Lourdes, by her former fitness trainer Carlos Leon. In July, Madonna, 50, took the rare step of issuing a formal denial of reports linking her to US baseball star Alex Rodriguez, adding in a statement: "My husband and I are not planning on getting a divorce." But according to The Sun, Ritchie " famous for gangster films including "Lock, Stock and Two Smoking Barrels" " has become frustrated, seeing her as a "dead weight around his neck" and now wants a divorce to be agreed quickly. "Guy's said if they were going to split, it has to be now " and their marriage will finally be over in a matter of weeks," the source told The Sun. The newspaper said that a statement "confirming their marriage is over has been prepared and is set to be released imminently." Madonna's mother-in-law, Ritchie's mother Lady Amber Leighton, made no comment to reporters who gathered outside her west London home, saying "We are not talking to press and we won't be all day." The singer herself was believed to be in Boston, according to the schedule of her world tour which includes dates in the United States and Canada over the next few weeks. Her next stop is Toronto on Saturday. Madonna, born Madonna Louise Ciccone, was previously married to US actor Sean Penn, from 1985 to 1989. In July, Madonna's estranged brother said he doubted she had an affair with baseball star Rodriguez, adding that she was committed to her marriage to Ritchie. "She's not the kind of person just to walk away," Christopher Ciccone told US television, adding that the pop legend will "do what's best for her family and her kids. "I think that she'll do her best to maintain the marriage and keep it going," he added.