A court in Vietnam has sentenced a group of dissidents to up to six years in prison for hanging pro-democracy banners and criticizing the communist government.

The alleged leader of the six dissidents - novelist Nguyen Xuan Nghia - received the heaviest sentence of six years' imprisonment for "spreading propaganda against the state."

The other five got terms ranging from two to four years for the same charges.

The court in the northern city of Haiphong also gave each of the defendants an additional term of three years' house arrest.

They were accused of hanging the banners on bridges in the city and in the neighboring province of Hai Duong, as well as posting photos of them on the Internet. Nghia was also accused of writing dozens of anti-government articles.  

His wife told the French news agency, AFP, the sentence is too harsh for her 60-year-old husband, saying he is already old and ill.

Vietnam has recently stepped up its crackdown against dissidents. Over the past few months, authorities have arrested at least five other pro-democracy activists on similar charges.

Western governments and international human rights groups have often criticized Vietnam for jailing people for peacefully expressing their views. Hanoi says it only imprisons people who break the law.

Some information for this report was provided by AFP and AP.