ScotRail engineers are planning strike action that they say is likely to severely disrupt travel to the Cop26 climate conference in Glasgow next month, as unions accuse management of risking “national embarrassment”.

Unite said workers had been left with no choice by the Abellio ScotRail management’s failure to make what it called a meaningful pay offer despite repeated action short of a strike since 24 September.

The planned 24-hour stoppages will take place on 18-19 October and 1-2, 10-11 and 12-13 November, and will affect stations including Glasgow Queen Street, Glasgow Central and Edinburgh Waverley. Global leaders and campaigners are due to gather in Scotland for the UN climate summit from 31 October.

Pat Mcilvogue, Unite’s industrial officer, said: “The talks have been spun out and cynically used as a delaying tactic to avoid the national embarrassment of having strike action during the Cop26 climate change conference, which is being held in Glasgow.

“We want the Scottish public to know that we have exhausted the process. Unite’s members have been holding action short of strike in an attempt to get Abellio ScotRail to wake up and to recognise the storm that they have created, to no effect. Now strike action will severely disrupt events and the Cop26 climate change conference due to this shambolic company.”

There are continuing disputes over pay, lack of investment and services cuts, and the RMT is also balloting on industrial action against ScotRail after a lengthy dispute over conductors’ pay.

On Monday Aslef, the RMT, the TSSA and Unite issued a joint statement saying that investment in Scotland’s railways, valuing staff, expanding services and making rail travel more affordable were essential to meeting environmental targets.

The Scottish government’s transport secretary, Graeme Dey, told BBC Radio Scotland that he was “actively encouraging” a resolution and that unions needed to “step back from some of the rhetoric dominating the agenda”.

He said: “I understand that later today the unions and ScotRail are meeting and a fresh offer is likely to be tabled. It’s one I hope that the unions will view in the spirit that it is going to be made and consider settling these disputes.”

A ScotRail spokesperson said: “We’re seeing customers gradually return to Scotland’s railway, but the scale of the financial situation ScotRail is facing is stark. We will continue to engage with the rail trade unions to find an agreement on pay and conditions.”