A spokesman for Turkey's Nationalist Movement Party (MHP) was killed and seven others were wounded in an attack on one of the far-right movement's campaign offices in Istanbul, media reports said Monday.

The attack took place late Sunday in the working class Esenyurt district shortly after the office's inauguration ahead of local polls due in March, the Dogan news agency reported.

Police have arrested six suspects in connection with the attack.

Celal Adan, a top leader of the party, which has the third largest grouping in parliament, pointed the finger at the banned separatist Kurdistan Workers' Party (PKK).

The Istanbul neighbourhood where the deadly attack occurred is home to a large Kurdish community and several of its members are reported to have demonstrated in front of the MHP premises before the inauguration.

A graft investigation into several of Prime Minister Recep Tayyip Erdogan's top political and business allies has plunged Turkey into a deep political crisis.