By Andrew Osborn
LONDON (Reuters) - Popular support for an independent Scotland has risen slightly in the last month even though Alex Salmond, the fiery nationalist leading the breakaway campaign, failed to win a high-profile TV debate, two opinion polls showed on Sunday.
With just five weeks to go before a Sept. 18 referendum in which Scots will decide whether to end their 307-year union with England and break up the United Kingdom, both polls showed support for independence had risen by 2 percentage points once undecided voters were excluded.
Like most other polls, both put the anti-independence campaign firmly in the lead however.
The surveys heartened nationalists who had expected Salmond, the leader of the pro-independence Scottish National Party (SNP), to easily win a TV debate with the leader of the anti-independence campaign, Alistair Darling, on Aug. 5.
In the event, Salmond unexpectedly failed to turn the U.S.-style debate into a victory for his cause.
But on Sunday, an ICM poll for the Scotland on Sunday newspaper put support for independence on 38 percent, up 4 points in a month. Support for the anti-independence camp was also higher, up 2 at 47 percent. Some 14 percent were undecided.
A second poll, undertaken by Panelbase, put support for the pro-independence camp at 42 percent, up 1 percentage point in a month. Support for the anti-independence camp fell by 2 points to 46 percent; 12 percent said they were undecided.
When the "don't knows" were stripped out, both polls, which were based on samples of about 1,000 people each, showed a 2 point swing towards the pro-independence campaign.
Professor John Curtice of Strathclyde University, an expert on the referendum, said the data showed that undecided voters were beginning to make up their mind.
He said the polls provided evidence that the "Yes" campaign had not been badly hurt by failure to win the TV debate.
"(This) means that a pro-independence campaign that had appeared to be at risk of being written off by the media will now enter the last month of campaigning with renewed heart – and that interest in and speculation about the outcome of the referendum will remain at fever pitch," said Curtice.
The debate is centred on how an independent Scotland could continue to use the pound despite Britain's main parties ruling out a formal currency union in the event of a "Yes" vote.
Darling, the leader of the "Better Together" anti-independence campaign, said on Saturday that Salmond's plan to use the pound "come what may" was irresponsible.
"If we left the UK and used the pound without any formal currency agreement, it would mean even bigger spending cuts and big increases in the cost of living for families in Scotland," he said.
The ICM poll showed signs that Darling's side was winning the currency debate with many Scots unconvinced by the pro-independence campaign's stance on the issue.
The polls were published a day after Australian Prime Minister Tony Abbott stirred debate by saying that an independent Scotland would not be in the world's best interests.
"What the Scots do is a matter for the Scots and not for a moment do I presume to tell Scottish voters which way they should vote," he told The Times newspaper. "But as a friend of Britain, as an observer from afar, it's hard to see how the world would be helped by an independent Scotland."
Salmond described the comments as "ludicrous" and "bewildering".
Salmond and Darling will go head to head on Aug. 25 in what is likely to be the final TV debate. Salmond has said he wished he'd better explained his stance on currency during the first debate and that he'd try harder next time.
(Editing by Stephen Powell)