Itanagar, Aug 24 - In a major setback to the Bharatiya Janata Party (BJP), the party's national secretary and former MP from Arunachal Pradesh West constituency Kiren Rijiju Monday joined the Congress party.

Rijiju formally resigned from the BJP to join the Congress at a simple function in state capital Itanagar.

Rijiju lost the last Lok Sabha election to Congress candidate Takam Sanjay.

Rijiju, 38, was the face of the BJP in the northeast. The party gave him the national secretary portfolio in a very short span of his political career.

'Soon after he lost the Lok Sabha election, Rijiju got in touch with the Congress as he was disillusioned with the BJP,' a Congress leader said.