David Cameron has left Scotland's fishing industry more vulnerable to "disastrous" regulations being discussed in Brussels this week by vetoing a new treaty, Alex Salmond has said.
The Scottish First Minister said he could have negotiated an acceptable deal on the treaty last week, accusing Mr Cameron of "irresponsible posturing".
He also told BBC Radio 4's Today programme that an independent Scotland would keep the pound - but joining the euro remains a long-term possibility.
"We have vital fishing talks in Brussels this week. Is it gong to be easier or harder to obtain the support of the countries we need to fend off regulations which would be disastrous for the Scottish fishing industry? Of course it will be harder," he said.
"In order to gain, in issues like fishing or indeed regional policy and the distribution of a variety of investment funds, you need to build alliances. It is very difficult to build alliances when you've just produced a situation where you are outvoted by 26 to one on an issue which touches on the whole future of the economies of Europe."
Asked if he would have signed up to the treaty, he said: "I think it was possible to produce a situation where agreement could have been produced on the treaty.
"What David Cameron was doing, spooked I suspect by Boris Johnson looking for his job, was to take a decision which might jeopardise the jobs of tens of thousands of other people. That's not leadership, that's isolationism and it's irresponsible posturing."
He said it was "absolutely clear-cut" that there would be no obligation on an independent Scotland to join the single currency - pointing to the example of Sweden.
"If Scotland becomes independent, we will be in the same position with regard to the euro as we are now: we will be part of the sterling area and I would propose we will remain part of the sterling area until such time it was in our interest to do something else," he said.
Joining the euro was "a long-term possibility, of course, but you would do it if economic circumstances were right and with the assent of the Scottish people".