Senegal's Prime Minister Ousmane Sonko has urged supporters of the ruling Pastef party to take revenge for alleged violence against them during the campaign for a parliamentary election this Sunday, raising concern among rights groups.

Supporters of the prime minister, who is also president of Pastef, clashed with police before a presidential election in March in some of the worst unrest in Senegal's history.

The country has been calm since Sonko's ally President Bassirou Diomaye Faye won the vote, defeating the candidate of then-president Macky Sall by a landslide.

But sporadic clashes between different party supporters have been reported in recent weeks as the country prepares for a parliamentary race that will ultimately decide the extent to which Faye and Sonko will be able to implement their agenda.

In a social media post, Sonko denounced attacks against Pastef supporters in the capital Dakar and other cities since campaigning started.

"May each patriot they have attacked and injured, be proportionally avenged. We will exercise our legitimate right to respond," he wrote.

The text accompanied a photo of a young man showing a gashing wound on his forearm.

A local civil society group reported a rise in violence during the first week of campaigning, including the headquarters of an opposition party set on fire in Dakar and clashes between supporters in central Senegal.

The interior ministry said on Monday it had been informed about acts of violence and sabotage against party caravans and other campaign activities, and called for calm.

Rights defender Alioune Tine urged politicians to show "moderation and wisdom" in their rhetoric and called on the interior ministry to invite different party representatives to meet in order to prevent harm.

"The verbal escalation has reached a critical threshold, we have the impression of going to war," Tine posted on X.

Pastef is competing against former ruling parties that have formed a coalition that unites ex-presidents Sall and Abdoulaye Wade.

Faye dissolved the opposition-led national assembly in September, accusing lawmakers of refusing to engage in meaningful talks on the budget and other proposals.