CAIRO, June 9 (Reuters) - Egypt will destroy all buildings along the Nile River and its tributaries that were erected illegally, the water and irrigation minister said on Monday, seeking to protect canals needed to help grow food.

The government will "not be complacent in the face of encroachment on the Nile River and its tributaries and streams", Minister Mohamed Abdel Motteleb was quoted as saying by the state news agency MENA.

Egypt is the world's biggest wheat importer, a drain on its precarious finances. Officials say illegal building along the Nile has increased in the turbulent years since a 2011 uprising which also scared away investors and tourists, major sources of foreign exchange.

Motteleb made his pledge in the Nile Delta town of Banha, in the heart of Egypt's breadbasket region north of Cairo.

He inspected an illegally built 13-storey apartment building that the army and interior ministry were preparing to blow up, MENA reported, describing the action as part of the state's efforts to restore the rule of law.

Former army chief Abdel Fattah al-Sisi was sworn in on Sunday, vowing to fix the economy and emphasising a need for hard work by all.

Water access is a major challenge for many Egyptian farmers. Buildings springing up in the densely populated Nile Delta result in loss of farmland and potential damage to irrigation systems.

The Agriculture Ministry estimates that some 30,000 feddans (acres) have been lost each year to unlicensed construction in the past three years, up from 10,000 feddans before the revolt.

Though millions of Egyptians are desperate for housing, authorities have recently taken to dynamiting buildings constructed without the required permits. (Reporting by Maggie Fick; Ruth Pitchford)