* Constitutional court says president risks breaking oath
* President Tanjda wants third term in office
By Abdoulaye Massalatchi
NIAMEY, May 26 (Reuters) - Niger’s constitutional court ruled unlawful on Tuesday a planned referendum to change the constitution to allow President Mamadou Tandja to stand for a third term in office.
The government of the uranium-rich desert state said this month that the septuagenarian leader, whose second and final term expires this year, would hold a plebiscite on constitutional changes to allow him to run again in November.
“The president ... cannot seek the amendment of the constitution without violating his oath,” the court said in a statement.
When the government announced Tandja’s decision to seek a referendum, it said he would take the advice of the constitutional court and of parliament, but not be bound by their decisions.
Around 20,000 people took to the streets this month to protest against the plan. At the weekend, some 20 political parties and civil society groups formed an anti-referendum coalition, the Front for the Defence of Democracy (FDD).
In Niger, companies such as France’s state-owned Areva are developing uranium mines in the north, an unstable region where a two-year rebellion by nomadic Tuaregs festers.
Tandja is trying to end the insurgency which has destabilised parts of the Sahara where al Qaeda also operates.
Regional body ECOWAS, which has 15 members, said last week that nearby countries could punish Niger with economic sanctions if it behaved undemocratically over the referendum proposal.
Other African leaders have abolished term limits, though not without opposition.
Algerian President Abdelaziz Bouteflika was allowed by lawmakers to stand for a third term, which he won in April. Cameroon’s President Paul Biya changed the constitution last year, a move which sparked rioting. (Writing by Daniel Magnowski; Editing by Robert Woodward)