THE SNP is on course to defeat Labour in North Lanarkshire in May's local elections, according to Labour's own internal research.

Leaked figures suggest the council, one of only two in Scotland with an outright Labour majority, will change hands with a massive swing to the Nationalists.

With the SNP also targeting Labour's majority in neighbouring Glasgow, losing North Lanarkshire, long-regarded as a party fortress, could mean a devastating double blow for Labour. The data obtained by the Sunday Herald reflects recent polls and the results from the 2011 Holyrood election, when the SNP ousted Labour MSPs from two of the five local constituencies.

At the 2007 council election, Labour won 40 of the 70 seats in North Lanarkshire on 49% of the vote, while the SNP won 23 seats on 31% of the vote.

As in Glasgow, the SNP had most of its candidates elected, but fielded too few to win a majority.

Now, however, the SNP is fielding over 40 candidates in North Lanarkshire's 20 wards, seriously threatening Labour's control.

According to Labour's own research, the SNP is expected to win around 47% of the vote for North Lanarkshire Council (NLC), with Labour getting 41%.

That would give the SNP 32 seats to Labour's 30, making the Nationalists the largest party, and putting them in pole position to form a coalition administration.

"I think the SNP has a good chance of being the biggest party or even a majority, although the latter is a bit of an ask," said a Labour insider.

Labour HQ admitted the figures came from a mathematical model based on the 2011 election, but denied they were solid predictions, as the party was campaigning to avoid such a result.

One Labour source said many of the party's NLC councillors were expecting "business as usual" on May 3, but would be in for a shock.

"The new candidates are all working their butts off, but quite a few of the old guard think they'll get in because they always get in. But it's been clear since last year's election result that it will be very difficult to turn the ship around in time for the council elections."

John Wilson, the SNP MSP for Central Scotland, said: "This leak clearly indicates the Labour brand in North Lanarkshire no longer has resonance. It augurs well for the SNP across Scotland and shows the direction of travel as we move towards the independence referendum."

A Scottish Labour spokesman said: "We are predicting an outright Labour majority in North Lanarkshire by persuading people who voted for the SNP last May to support Labour this time. With a rise in support for Labour locally, evidenced by a stunning council by-election victory where Labour won over 50% of the vote, that strategy is working."