Glasgow school janitors are to take strike action on the date of the Scottish Parliament election in a move which could affect polling places.

It is not yet known whether Glasgow City Council has made contingency plans to ensure the affected schools will open to voters at 7am on May 5.

The walkout by primary school janitors on May 4, 5 and 6 will be the third three-day strike in as many months.

A spokeswoman for Glasgow City Council said officials are “checking the status of all our primary schools on May 5," many of which will be designated as polling places.

More than 130 staff are in a stand-off with employer Cordia over Working Context and Demands (WCD) payments.

Some Cordia employees are allocated points for duties which involve physical demand, working outdoors or dealing with unpleasant conditions.

If enough points are accumulated, additional WCD rates are triggered which range from £500 to £1000 a year.

But primary school janitors are not currently entitled to the pensionable payments and Unison members began industrial action on January 19 by refusing to carry out some duties.

They then went on strike from March 11 to 13 and from April 20 to 22.

Unison Glasgow branch secretary Brian Smith said public protests will be held at Cordia’s headquarters in Borron Street on May 4 from 8am.

There will also be a protest at Glasgow City Chambers on May 4 from 12:30pm.

In an email to members Mr Smith said: “You are encouraged to get along to and show your support.”

Branch officer Sam Macartney has previously accused Cordia of “refusing to even meet these hard working janitors and their trade union”.

He added: “Unison is very clear that school janitors meet the criteria to be awarded this payment.”

A Cordia spokesman responded by insisting internal procedures led to a rejection of Unison’s claim for WCD payments for janitors.

The spokesman added: “Cordia has completely exhausted all internal processes after negotiations with Unison and is not required to convene a meeting to further negotiate when at this stage, there is no possibility of a settlement.”