Around 500 journalists at the two newspapers have initiated a 48-hour long strike.
A month ago, 93 percent of the unionized employees voted for the strike. They accuse the owner of Guardian Media Group (GMG), Scott Trust, of "betrayal". This is due to the potential sale of The Observer to Tortoise Media.
Tortoise is said to have contacted GMG with an offer to buy the newspaper. They have also stated that The Observer will continue to be published.
More than 70 well-known British cultural personalities, including actors Hugh Grant, Damian Lewis, and Sienna Miller, have in an open letter urged Trust "to immediately reject this ill-conceived offer".
The Guardian will continue to publish on the website and issue the paper edition as usual.
