Manila: Two foreign nationals were arrested by agents of the bureau of immigration for entering the country through the so-called "southern back door".

Gul Hussain, a Pakistani, and Australian Steven Nicol Herbert, were arrested separately by Bureau of Immigration intelligence operatives at their residence in Southern Philippines' Zamboanga City on December 20, said Immigration Commissioner Ricardo David.

The two had tried to take advantage of the lax border control checks and easy transit by sea and land transportation in southern Philippines.

David said he issued orders for the arrest of the two foreigners after immigration officers were tipped off about the presence of foreigners in Zamboanga City.

He said that with the arrest of the two, the bureau will launch a sustained drive to arrest more foreigners hiding in southern Philippines.

"I have directed our intelligence operatives in the South to conduct further surveillance operations of aliens suspected of entering the country via the backdoor," he added.

According to Maria Antonette Mangrobang, acting immigrations intelligence chief, Herbert arrived at the port of Bongao, Tawi-Tawi from Sampona, Malaysia on October 1.

The Australian had been blacklisted by immigration in March last year after he was ordered to leave the country for failure to pay his permit extension fees.

As for Hussain, Mangrobang said the Pakistani refused to divulge how he entered the country.