France has said it plans to offer incentives to more immigrants - especially those from Africa - to return home voluntarily.  New Immigration Minister Brice Hortefeux said a family with two children would be paid 6,000 euros (£4,068) to return to their country.  In 2005-2006, a similar scheme was taken up by some 3,000 families.  France is home to about two million immigrants from north and sub-Saharan Africa, according to a 2004 census.  We must increase this measure to help voluntarily return. I am very clearly committed to doing that, Mr Hortefeux told Frances RFI radio.  Mr Hortefeux last week was named immigration minister by newly-elected President Nicolas Sarkozy.  Mr Sarkozy has warned that France is exasperated by uncontrolled immigration.  France was hit by a series of riots in the immigrant-heavy suburbs in 2005.