Iranian security forces have killed in a fresh clash four members of an extremist militant group behind an attack that left 14 Iranian border guards martyred, a top border guard commander said Tuesday.

Iranian security forces have killed in a fresh clash four members of an extremist militant group behind an attack that left 14 Iranian border guards martyred, a top border guard commander said Tuesday.

"We clashed with Jaish-ul Adl and killed four of them," the Fars news agency quoted brigadier General Hussein Zolfaqari, commander of Iran's border guards, as saying.

He did not say when or where the new clash took place.

"Whatever measure they take against us, our response will be more crushing," Zolfaqari said.

In a press briefing in the afternoon, he said that 20 "bandits" had been killed in 67 clashes near the border since March 2013, the Mehr news agency reported.

The general also warned that Iran "reserves the right to pursue the bandits on Pakistani soil," adding that his unit had informed its Pakistani counterparts of this, Mehr added.

Tehran has demanded Islamabad take "measures to control the borders more seriously," saying the militants had crossed from Pakistan and fled back across the border after the attack.

Iran says it plans to exert more pressure on Pakistan to prevent such attacks.

"A deputy interior minister will visit Pakistan to discuss the attack," foreign ministry spokeswoman Marzieh Afkham said Tuesday during her weekly briefing.