Former Zambian Finance Minister Katele Kalumba has been convicted of corruption. A court in Lusaka jailed him for five years with hard labour in connection with irregular payments of $25m (£17m) to two American security firms. The offences were committed during the 1991-2001 presidency of Frederick Chiluba. Mr Chiluba himself was acquitted of corruption charges in 2009 after a six-year trial. On Wednesday, six other people, including former officials in the finance ministry, were also found guilty of corruption. Mr Kalumba and his co-defendents had denied the charges against them. It was not immediately clear if they planned to appeal.