THE ruling Labour Party administration in Glasgow is facing a series of by-elections, heaping more pressure on the party ahead of next year's Scottish Parliament poll.

The SNP has triggered two following the election of two of its city councillors as Westminster MPs last week.

A third was confirmed after it emerged one of the authority's Green councillors was standing down due to ill health.

Martin Docherty and Alison Thewliss returned from their first week London for a meeting of today's full council, where they have announced it would be their last.

Following the conclusion of the meeting the Scottish Greens announced that Liam Hainey, who was elected in 2012, would also stand down from his seat in Langside, on the city's south side.

A date will be set for all three by-elections by the city's returning officer but they are expected to be held within the next two to three months.

Mr Docherty's departure to become MP for West Dunbartonshire will force an election within council leader Gordon Matheson's city centre ward. Ms Thewliss had represented Calton, in the east end before defeating Anas Sarwar to become Glasgow Central MP.

The decision is being seen as a calculated move by the SNP to deepen the anxiety of Labour within the city, with Cllr Matheson's future being openly discussed following last week's whitewash. The party was under no obligation to trigger the polls and had discussed the merits since last Thursday.

It is unclear if any other of the other dozen or SNP councillors elected as an MP last week will resign to instigate by-elections.

One Labour source said the decision to force the by elections was an attempt to "cut the legs of the party in Glasgow", adding: "If Labour delivers more of the same the outcome will be the same as last week. Labour would need to win and win convincingly."

An SNP insider said the party had decided that potential defeat in a city where Labour surprisingly romped home to a majority win in the 2012 council elections was worth the risk.

The source said: "If we win both any problems bubbling beneath the surface within the council's Labour Group will be thrust to the fore. They've much more to lose than we do."

Glasgow's SNP group leader Susan Aitken said: "The SNP in Glasgow  take absolutely nothing for granted and we will campaign very hard in any by-elections in the Calton and Anderston/City wards when they are called. "Obviously though, our campaign benefits from a strong start due to the hard work of SNP activists during the general election and the superb results they achieved in these wards, as well as from the legacy of goodwill that Martin and Alison's work as councillors has left us.

"Our group's loss is the Westminster group's gain, but it's entirely understandable that they both want to dedicate themselves to their new roles as the MPs for Glasgow Central and West Dunbartonshire."

Confirming his resignation in a letter to the city's Lord Provost, Mr Hainey said: "It has been a privilege to serve my constituents and the people of Glasgow but, with regret, my health and family circumstances mean that I do not feel that I am able to render the service to the people of my ward which they deserve."

A spokesman for Glasgow Labour said: "We aim to win these opposition seats. If we do, our overall majority will increase further. If not, we will still be a majority administration and will complete the implementation of our 2012 manifesto".