Three policemen were shot dead by suspected al-Qaeda members in a village near the border with Burkina Faso.
One soldier was killed and two others wounded when a military convoy was attacked close to Nigeria's border.
Thursday's attacks came three days before Sunday's controversial presidential run-off election.
The opposition has said they will not recognise the results of the vote, and their candidate Hama Amadou, is currently receiving medical treatment in Paris after spending months in jail.
Niger's Interior Minister Hassimi Massaoudou says the attack in a market in Dolbel village close to Burkina Faso was the work of al-Qaeda in the Islamic Magrib (AQIM), which has been active in the region.
"The attackers were repelled, and we are currently sweeping the area," he told the AFP news agency.
The other attack was carried out by four suicide bombers in southern Diffa region that has often been targeted by Nigeria's Boko Haram insurgents.
A fifth suicide bomber, a young girl, was prevented from detonating her vest, Mr Massaoudou added.
Niger has porous borders with Libya, Algeria, Mali and Burkina Faso, which have all been hit by AQIM recently, and Nigeria to the south - making it vulnerable to Islamist attacks.
The country is rated by the UN as one of the world's least-developed nations and was recently named as the worst country to live in.
Islamist militants from al-Qaeda and Boko Haram have killed four security forces in two separate attacks in Niger, officials have said.