An influential African mediator, seeking to ward off an election crisis in Senegal, says he has proposed President Abdoulaye Wade limit his stay in power to two years if he is re-elected.

Former Nigerian President Olusegun Obasanjo, an envoy of the African Union and West Africa's ECOWAS bloc, said he made the proposal after Wade's rivals called for him to serve just one year in power if he won. The incumbent's camp said he should be given three years.

Last-minute talks ahead of Sunday's poll highlight growing fears that Senegal, long one of West Africa's most stable democracies, is headed towards a post-election crisis. Clashes ahead of the vote have already killed six people.

It is just a proposal and neither side has agreed, Obasanjo told reporters on Saturday after several days of meetings with Wade's camp and the opposition.

Senegal has seen days of street protests to try to reverse a decision by the constitutional council to allow Wade to stand but the vote looks set to go ahead with the octogenarian leader as one of 14 candidates.

Wade's rivals and opposition groups say his candidacy is illegal due to term limits in the constitution. The president argues restrictions were brought in after he started his first stint in power, so do not count.

The United States has called his decision to run again regrettable and France's foreign minister said it was time for Senegal's younger generation to take power, comments Wade's government furiously rejected as interference.

Alioune Tine, head of the M23 movement of opposition parties and civil society groups, told Reuters earlier that, under the proposition, the period after the election would be used to calm tensions and push through reforms of Senegal's institutions.

Wade's camp has claimed new infrastructure projects as proof of his ability to deliver change to the poor West African state but his critics complain of waste and corruption, and say not enough has been done to improve the lives of ordinary Senegalese.

Senegal's opposition parties have so far failed to mount a coordinated challenge to Wade's candidacy and have put forward 13 people to take on the incumbent, despite the simmering frustrations over his time in power, especially in urban areas.

(Reporting by Diadie Ba and Pascal Fletcher; Writing by David Lewis; Editing by Andrew Roche)