Tehran (AFP) - Iran denied claims it had closed its main border crossing into Turkey Wednesday after an Iranian truck was torched in a fresh attack on vehicles entering from the Islamic republic.

"All the country's land borders... including the one in Bazargan, are open and traffic is passing through," interior ministry Director General Majid Agha-Babaie said.

"None of the border (crossings) are closed and none will be," he added in remarks carried by state news agency IRNA.

Earlier, road traffic organisation chief Davoud Keshavarzian was quoted as saying the crossing at Bazargan in the northwest had been closed to traffic into Turkey but not from the opposite direction.

He said that came following a new attack Tuesday evening on an Iranian truck in Turkey.

Another official quoted by IRNA said Turkish vehicles were crossing the border headed home, but that Iranian drivers were refusing to enter Turkey.

Keshavarzian did not say who carried out the attack or what the motive was, but there has been growing unrest in Turkey in recent weeks involving Kurdish separatists.

He said the driver of the torched truck was not killed, adding that he had spoken to the Turkish ambassador and asked that "the Turkish government ensure the safety of Iranian drivers in Turkey as Iran does for Turkish drivers".

On Saturday, Iran warned its citizens to avoid land travel to neighbouring Turkey after an Iranian bus was attacked by gunmen in the east of the country.

At the end of July, Iran suspended train services between Ankara and Tehran after two bomb blasts on the railway in eastern Turkey.

And a bomb exploded last month on the Iran-Turkey gas pipeline in Agri province in eastern Turkey.

Attacks have been on the rise since a bombing killed 32 people in a mainly Kurdish town in southern Turkey on July 20, ending a two-year truce between Turkey and the rebel Kurdistan Workers' Party (PKK), which is active in eastern Turkey.

Turkey claimed the bombing was carried out by the jihadist Islamic State (IS) group, and launched air strikes on IS positions in north Syria, as well as PKK targets in northern Iraq.

The events have sparked a cycle of reprisals between the Turkish state and the Kurdish rebels.