A keynote speech by Cisco Systems chief executive John Chambers was interrupted by a group of demonstrators at the company's annual Cisco Live event in San Francisco.

A group of demonstrators is from Service Employees International Union which were laid off from janitorial positions at Cisco's San Jose headquarters. The demonstrators started making noise just after Chambers made a comment about the annual Cisco event.

In June a worker's union reported on a hunger strike staged by janitors following a layoff in February of 40 percent of Cisco's janitorial staff.

In the first week of June this year, Service Employees International Union website reported that dozen workers staged by janitors strike for a two days hunger strike following a layoff in February of Cisco's janitorial staff.

The union says the janitors were laid off by ABM Janitorial Services and is calling on Cisco to tell ABM to restore the workers.

Chambers paused twice at the start of his speech but later continue his talk after the interruption.