"Four soldiers have died as martyrs and six were wounded in an ambush against a military patrol," the Wataniya 1 channel reported, quoting the defence ministry.
The channel had earlier given a toll of two dead and three wounded.
It gave no further details and officials at the defence ministry could not be immediately reached.
A military source told AFP that the attack took place not far from the city of Sbeitla. Several Tunisian media reported that the soldiers came under fire with a rocket-propelled grenade.
Authorities have blamed the main armed group active in the area, the al-Qaeda-linked Okba Ibn Nafaa Brigade, for a series of attacks including last month's massacre at the national museum in Tunis that left 21 foreign tourists and a policeman dead.
Tunisian security forces said last month they had killed the alleged mastermind of the attack -- Lokmane Abou Sakhr -- along with at least eight other members of the group.