A court in the coastal city of Mombasa has sentenced a British national, who authorities say is an extremist who plotted attacks against the country, to nine years in prison for attempting to illegally acquire Kenyan identification documents.

Justice Martin Muya said Wednesday the prosecution has proved that Jermain Grant had attempted to illegally acquire a birth certificate, a Kenyan identification card and a primary school leaving certificate. The high court found Grant guilty after the prosecution appealed a previous acquittal.

Authorities believe Grant was part of a cell with another British national, Samantha Lewthwaite, that was planning attacks over Christmas 2012. Lewthwaite is the widow of Jermain Lindsay, one of the bombers who took part in the July 7 2005 attack on London that killed 52 people.