Europe is preparing the way for sanctions against Iceland and the Faroe Islands over the so-called "mackerel wars", BBC Scotland has learned.
The two countries announced plans for big rises in their mackerel catches, but Scottish fishermen said stocks would be devastated if that happened.
Europe's Fisheries Commissioner, Maria Damanaki, is now believed to be instigating changes in regulations.
These would result in sanctions against the two countries being implemented.
Mackerel is the Scottish fleet's most valuable stock. Talks held last week failed to resolve the on-going dispute.
The meeting, with the EU and Norway in Copenhagen, ended with the Faroese refusing to sign a deal that would set mackerel catch levels for 2011.
Scottish Fisheries Secretary Richard Lochhead said: "We were extremely frustrated by last week's breakdown in mackerel talks.
"I am pleased that Commissioner Damanaki has confirmed she will endeavour to take strong action and put in place the necessary tools to apply meaningful sanctions. We cannot reward reckless behaviour."
Ian Gatt, chief executive of the Scottish Pelagic Fishermen's Association, said Mrs Damanaki had indicated she was consulting on ways to restrict landings of Icelandic mackerel into the EU.
The commissioner is also pressing for regulations that could result in the ban on imports of fish from countries acting outside international fishery agreements.
Mr Gatt added: "It is vitally important to convert these words into action as we have had such statements of intent for several months now."
Scottish Conservative MEP Struan Stevenson said: "Right at the start of this dispute I called for tough sanctions against Iceland and the Faroes, including a blockade at EU ports.
"I had hoped we could resolve this disagreement by negotiation, but it seems Iceland and the Faroes simply don't want to be reasonable.
"Commissioner Damanaki is absolutely right to be considering firm action. Iceland and the Faroes cannot simply get away with endangering a migratory fish stock shared by many nations."
Iceland and the Faroes sparked outrage when they unilaterally set quotas in their own waters. Iceland recently denied that it had walked away from talks.
The country's key negotiator on mackerel fisheries, Tomas Heidar, told BBC Scotland's news website: "It was simply a joint conclusion that an agreement on the comprehensive management of mackerel fisheries next year could not be reached.
"Iceland has showed increased flexibility at this last coastal states meeting but that was in vain primarily because of Norway's unflexible position that a share for Iceland beyond 3.1% was unacceptable."
Earlier this year angry Scottish fishermen prevented a Faroese vessel from landing mackerel at Peterhead.
Commissioner Damanaki was presented with a gift of mackerel to highlight the concerns of the industry in September when she visited Aberdeen.