Counter-terrorism police have arrested an Iraqi, an Iranian and three Pakistanis allegedly planning attacks in insurgency-hit southern Afghanistan, the interior ministry said Wednesday.

The men had entered Afghanistan's Nimroz province from neighbouring Iran, ministry spokesman Yousuf Stanizai said.

"They are all terrorists. They had crossed illegally into Nimroz from Iran and wanted to go to other provinces to carry out terrorist attacks," he told AFP.

"They all had documents proving their identities. The investigation is ongoing."

Stanizai said the Iraqi, whose name was not disclosed, was on his way to southern Kandahar province.

The province is a hotbed of an insurgency that erupted after the Taliban government was ousted in late 2001. It has suffered frequent suicide and car bomb attacks that officials often blame on foreigners allied with the Taliban.