The Climate Minister's adamant another blank Emissions Trading Scheme auction should not be seen as a failure

Zero units were sold in the September auction, and no bids were received -- meaning the credits will be rolled over to the next auction.

The Greens are calling-out the Government, saying successive auctions have failed.

But Minister Simon Watts says this is the way the auctions should work when there's not enough demand.

He says it signals the fact there's adequate supply in the secondary market.