Protesters and police clashed Thursday outside Senegal's parliament as it debated widely criticised changes to election laws, with at least one policeman hurt in the violence, an AFP journalist said.

The building was under heavy security after the opposition called for demonstrations against the project, which it claims is an attempt by ageing President Abdoulaye Wade to line up his son for succession.

As clashes erupted, parliament, dominated by Wade supporters, began debating the changes that would introduce a vice president on the presidential ticket for elections in February.

If one ticket wins more than 25 percent of the votes, it would be declared winner, avoiding a second-round runoff. This is up from the current 50 percent requirement.