South Island emergency services are battling two vegetation fires in Blenheim and Christchurch

Two helicopters are heading to the Christchurch blaze, burning by Port Hills Rd on the city side of the Lyttelton Tunnel.

Another two helicopters are en route to help four crews at a grass fire by State Highway 1 and Redwood Pass Rd in Blenheim - covering two to three hectares.

Both fires are affecting traffic.