An EU ban on the practice of discarding unwanted fish at sea is "a step in the right direction", Environment Secretary Richard Lochhead has said.

European politicians have now reached agreement on the issue but critics say it is "worthless without ambitious binding targets".

It follows a meeting of the EU Council of Ministers in Luxembourg, which agreed on a way forward for reforming the Common Fisheries Policy.

No firm date was set, although the council has published a provisional date to ban the discarding of fish such as mackerel and herring by January 1 2014. Banning the discard of whitefish such as cod, haddock, plaice and sole will be phased in a year after that and will be fully in place by January 1 2018.

EU rules give fishermen quotas for certain fish but they can carry on fishing once the limits are reached as long as they do not bring any more of that species to shore. This means tonnes of edible fish are thrown back to sea as discards, accounting for as much as 90% of the catch in some fisheries.

The practice has prompted public outrage in the UK.

Mr Lochhead described the time-frame set out as "a significant step in the right direction after more than 30 years of discard inaction".

In light of the Scottish Government wanting a ban on all discards in place by 2016-17, the Environment and Rural Affairs Secretary said: "It is important to recognise this is not the end of the road. And as this process unfolds there will be ample time for the time-frame to be revised in favour of our more ambitious one."

He said: "I am proud of the role Scotland has played in securing these initial changes and our constant engagement with the UK Government, the commission and other member states has borne fruit and we will continue to seek more improvements as the negotiations progress."

Euan Dunn, head of marine policy at the RSPB, said that while he "heard some of the right words" from the council, these are "worthless without ambitious binding targets to put things right".

Mr Dunn said: "Without these, the aim of ending overfishing and banning discards will fall by the wayside as soon as politics and difficult decisions get in the way."

Bertie Armstrong, chief executive of the Scottish Fishermen's Federation, said: "It is not possible to reduce or eliminate discards simply by putting a number on a page in any new regulations.

"We all abhor discards but reducing or even eliminating discards in complex mixed fisheries can only be achieved by practical management on a regional scale."

Green MSP Alison Johnstone said: "The view of those who care about the sustainability of the sector is that these talks have been a flop rather than a success. We owe it to future generations to match ambitious words with action."