ISLAMABAD: Iranian Foreign Minister Javed Zarif is arriving here on Wednesday on a previously unscheduled visit for talks on a recent terrorist attack near the Pak-Iran border in which at least 10 Iranian border guards were killed.

Mr Zarif will meet Adviser to the PM on Foreign Affairs Sartaj Aziz and a number of other senior leaders during his day-long trip.

The Iranian foreign minister had earlier said that Tehran `will spare no effort in following up the case through diplomatic channels and punishing terrorist thugs`.

Border security has been a major irritant in the bilateral relations that have been marred by mutual mistrust.Iranians accuse Pakistan of turning a blind eye to the presence of terrorist groups along the border from where they have carried out severalattacks in their territory.

The bilateral border mechanism, established for dealing with these matters, has not been functioning effectively. Iran has taken an unprecedentedly tougher line on the recent terrorist incident.

President Hassan Rouhani had in a letter asked Prime Minister Nawaz Sharif to take action against the terrorist groups and punish them to deter future incidents.

Pakistan`s ambassador to Iran was also summoned over the attack.

The Foreign Office had in response to Iranian protests offered cooperation for strengthening coordination and security along the border.