Tunisian authorities arrested a Libyan man in a car packed with Kalashnikov rifle cartridges in the south of the country, 80 km (50 miles) from the border with Libya, a police officer said.
The officer at the scene told Reuters by telephone that police had arrested a second man who was transporting grenades.
There were no further details on the separate arrests in the southern town of Bir Amir.
Arab and Western officials have said that Al Qaeda could be exploiting the Libyan conflict to acquire weapons and smuggle them into other countries.
Tunisian state news agency TAP said the men were both Libyans and one had a hand grenade. It quoted interior ministry sources denying that the men had munitions.
A senior security official in neighbouring Algeria told Reuters last month there were signs Al Qaeda was working to acquire arms to smuggle them to a stronghold in northern Mali.
The Algerian official described a convoy of Toyota pick-up trucks which had left eastern Libya and arrived in Mali after it crossed through Chad and Niger.
In that case the trucks unloaded Russian-made RPG-7 anti-tank rocket-propelled grenades, Kalashnikov heavy machine guns, Kalashnikov rifles, explosives and ammunition, the official said.