The conservative opposition parties in Germany have launched a petition to collect signatures against government plans to reform the country's citizenship laws.

The Christian Democrat leader, Wolfgang Schaeuble, singled out a proposal under which foreigners could adopt German citizenship while retaining their own nationality and said this would allow foreign crime gangs to operate in Germany.

The state premier in Bavaria Edmund Stoiber also criticised the reforms, saying they posed a greater threat to the country than the urban terrorism of the nineteen-seventies and -eighties.

The centre-left government says the conservatives are trying to mobilise prejudice against immigrants.

The new law would grant automatic citizenship to third generation foreigners born in Germany and allow foreigners who have lived in the country for eight years to apply for naturalisation.