The incoming Spanish government is coming under intense diplomatic pressure to fall in line with European Union proposals to ban wasteful fishing practices, after a leaked document showed that the previous administration was planning to derail the plans.

The government must choose between supporting its new allies in the EU, on which Spain’s economic future depends, or bowing to its powerful fishing industry.

As Europe’s biggest fishing industry, Spain could hold the key to the success or failure of the reforms, which would prevent fishermen discarding edible fish at sea.

But according to a secret government document seen by the Guardian, Spain’s previous administration was plotting a last-ditch attempt to bring down the reforms, and allow Spanish fishermen to continue throwing away edible fish as they have been doing so for decades

The document is dated November 2, just weeks before the general election of November 20, showing that lobbying for a continuation of discards was a key policy for the outgoing socialist government even in its dying days.

Hugh Fearnley-Whittingstall, the chef and Guardian food writer who has led the high-profile Fish Fight campaign against discards, said: “Throwing away thousands of tonnes of perfectly edible fish is completely unacceptable – and I’m sure that if the Spanish public knew about the scale of the problem in their fishing fleet, they too would demand an end to discards, and support a radical overhaul of the EU’s common fisheries policy.”

He said that early in 2012, the campaign, which Europe’s fisheries chief Maria Damanaki has credited as an important factor in generating public support for her anti-discards policy, would be extended to the rest of Europe.

Fearnley-Whittingstall said: “We’re planning to launch our Fish Fight campaign in Spain, as well as in France, Germany and Poland. We need to get the whole of Europe as outraged about this senseless waste of fish as we are here in Britain. Then perhaps the Spanish government will spend more time working towards developing a sustainable and effective solution to the discards problem, rather than trying to build alliances to derail the proposed reforms.”

If the new government reverses the stance of its predecessor, it would mark a major victory in the fight to end discards, which result in European fishermen throwing away – dead – as much as two-thirds of their catches of live, edible fish.

Discards are a perverse result of the current EU fishing policy: whenever fishermen accidentally land fish for which they have no quota, or when they exceed their quota, they must throw part of the catch away. Nearly three-quarters of the EU’s fish stocks are now estimated to be overexploited.

As Europe’s biggest fishing nation, Spain is in pole position to obstruct or water down the reforms, which are aimed at protecting dwindling fish stocks and which the European Commission wants to finalise in 2012.

2012 Guardian News and Media Limited