North Sea workers' strike to disrupt Shell operations - union

* 24-hour strike on seven Shell (LSE: RDSB.L - news) platforms set for July 26

* To be followed by three-hour strikes in coming weeks

* Maintenance workers strike may not impact production

* Shell making contingency plans to ensure safety - source (Updates throughout)

By Karolin Schaps

LONDON, July 18 (Reuters) - A 24-hour strike of Wood Group oil and gas maintenance workers will "severely disrupt" operations at several Royal Dutch Shell (Xetra: A0ET6Q - news) platforms in the North Sea where they are employed, labour union Unite said on Monday.

The strike action scheduled for July 26 will be the first walkout by UK North Sea workers in ten years as oil and gas staff are angered by pay cuts and tougher working schedules brought on by cost savings amid the oil price crash.

The workers will also undertake several three-hour strikes over the following weeks, a union representative said.

At total of seven Shell platforms, including the historic Brent facility, will be affected by the strike of Wood Group employees who carry out maintenance. This means production from the platforms may not necessarily be impacted.

Shell is making contingency arrangements to ensure safety is not affected by the strike action, a person at the company said.

"It is anticipated that the action will severely disrupt operations on the Shell platforms," the union said in a statement.

The platforms affected are Brent Alpha, Bravo and Charlie, Gannet, Nelson, Curlew and Shearwater. Shell's Brent Delta platform, which is being decommissioned, is also included.

An overwhelming number of employees backed strike action in a ballot carried out last week.

Wood Group said it was continuing to engage with employees and labour unions to reach a resolution.

Shell said it hoped Wood Group and its employees would come to an agreement. (Editing by David Clarke and Mark Potter)