Niger's President Mamadou Tandja, 71, is claiming victory in a referendum he called to change the constitution and run for a third term in office. Correspondents in the capital, Niamey, say giant posters have gone up in the city bearing a message of thanks to voters from Mr Tandja. Official results are expected later on Friday. Niger's electoral commission has said there was a 68% turnout. Opposition groups had urged a boycott and the EU and UN expressed concerns. However, the country's electoral commission says the president is heading for an overwhelming win. On Thursday, the opposition grouping Co-ordination of Democratic Forces for the Republic (CFDR) said its investigations showed that turnout was as low as 4%. The BBC's Idy Baraou said in Niamey that Tuesday's voting was slow with small groups of people turning up at at polling stations. Security forces fired tear gas at opposition supporters in their northern stronghold of Illela and some were also arrested in Dosso in the east, accused of trying to disrupt the poll, he said. The president dissolved both parliament and the constitutional court to push through the referendum. His backers say he has boosted living standards during 10 years in power and deserves to remain in office. The president says he needs more time to complete multi-billion-dollar projects such as a uranium mine, an oil refinery and a dam on the River Niger. But his critics portray him as a classic strongman determined to hold on to power so he can benefit financially from the projects he has started. The European Union has already suspended an aid payment and warned of "serious consequences" for its co-operation with Niger if the president carries through his plans. Source: BBC