Updated 3.45pm: Warning signs have been put up at popular Takapuna beach over water pollution.

The Auckland Council's investigating the source of the contamination. Until then swimmers are being told it's not safe to hit the water.

The warning comes after test results done regularly on 63 beaches across Auckland.

The test results from neighbouring beaches –Milford, Mairangi Bay and Long Bay- have been inconclusive and further testing is being carried out there to confirm if there is a significant risk.

Auckland Council hopes to find out this afternoon if a ban on swimming will have to be extended to other North Shore beaches.

Earlier this week similar signs went up at Clarks Beach and at Laingholm Beach but tests since have shown good results.