The union says more than 40 staff stayed away from their desks in a protest over pay on Monday, Tuesday and Wednesday, but no resolution has been found.
A spokesman for Newsquest South London said all its papers and editions had been published as normal.
Members are unhappy with a three per cent pay offer.
During the industrial action the Guardian’s newspapers offices in Morden and Croydon were picketed and strikers also handed out leaflets in Balham, Tooting and Wimbledon town centres.
Leaflets were also handed out outside a Newsquest office in Cheam.
A Newsquest spokesman said: “We are in discussions regarding an alleged breach of the DTI Code of Conduct on picketing at one of our satellite offices.”
Father of Chapel David Tilley said members would now meet to decide what to do next.
He told HoldtheFrontPage: “There has been a lot of very positive support. Sadiq Khan, who is the MP for Tooting, came to see us on Monday and is asking for a meeting with management.
“There has also been a lot of public support and we have collected a 1,000 signature petition.”
They say they will take a ten-minute screen break together every morning and a one-hour lunch break together every day from August 9 until further notice. They claim that 12 editorial posts are currently vacant and that this has put pressure on existing staff.
Sheffield Newspapers mother of chapel Julia Armstrong said: “The chapel feels enough is enough and that it is time to do something about staffing.
“We are stressed out, we are missing time with our families and the quality of the papers is suffering.”