The Scottish first minister, Alex Salmond, has claimed David Cameron's determination to force an early referendum on independence for Scotland will increase support for leaving the United Kingdom.

The SNP leader said the prime minister had no mandate to set the rules for an independence referendum, describing Cameron as "almost Thatcher-esque".

Salmond added, however, that a deal could be struck on how the poll was conducted. He was speaking on BBC Radio 4's Today programme on Wednesday, a day after the government in Edinburgh insisted it would organise the referendum in autumn 2014, 700 years after the battle of Bannockburn.

Salmond blamed Cameron for inflaming the growing constitutional crisis by starting to pull strings and set conditions. "I thought his intervention at the weekend was almost Thatcher-esque in its nature, the idea that London knows best and it is operating in our best interests but wanting to set the ground rules for our referendum despite the fact it has got no mandate whatsoever for doing so."

Asked whether his government would put only a yes/no question on the ballot paper as Cameron wanted, Salmond said the legitimate view of people who wanted greater devolution should not be ruled out at this stage.

The attitude of ministers in London had significantly changed recently, he said. "It was not the language they were using, the language of respect, when the SNP won a huge majority in last year's election."

Salmond insisted he was "always constructive about these things" and indicated a deal could be struck. "As long as it is recognised that [there is a] mandate of the Scottish parliament to organise and hold a referendum – it must be a referendum built in Scotland and decided by the Scottish people – as long as that is recognised, I'm sure politicians north and south of the border are capable of coming to an agreement some time this year about the ground rules for such a poll and certainly that will be my attitude."

Former Labour chancellor Alistair Darling, also speaking on the Today programme, said Labour must work with Liberal Democrats and Conservatives if those wanting to save the union with Scotland were to be successful. "Let's be clear, the only reason we have been put off until 2014 is because Alex Salmond doesn't think he can win just now and he is playing for time.

"The sooner we get on to big questions, like for example what currency we will have – and Alex Salmond after all these years in politics still can't tell us that – would we be going into the euro with all the strictures they are now visiting on members, how much debt are we going to have, how do we see Scotland's future? These are the big arguments that we need to engage in, " said Darling, MP for Edinburgh South West.

"Get the process sorted out, let us get on to the merits of the argument because the sooner we treat people in Scotland like the grown-ups we are and we have a proper discussion about that the better it will be."

Former Liberal Democrat leader Sir Menzies Campbell told the programme: "Remember this – independence isn't just for Christmas. This is asking people to make a decision to bring to an end 300 years of constitutional arrangements.

"There is an important distinction between a political mandate and lawful authority, legality, and it seems to me that it would be very, very difficult and quite wrong for these constitutional issues to become embroiled in legality as to how we make that decision."