Two 24-hour Tube strikes by three unions were suspended at the last hour on Monday evening (August 24) following talks with London Underground.

Unite, RMT and TSSA agreed to suspend the industrial action following talks with Underground bosses at Acas.

Aslef had previously announced it would not be taking part in the walk-outs planned to take place from Tuesday evening (August 25) and Thursday evening (August 27).

But the row over the introduction of a Night Tube service could continue to rattle on, the unions warned.

And the RMT said further strikes - in September - could take place.

General secretary Mick Cash said, in a statement: "Tthe disputes are not over and there are still a few matters that need further attention before we can reach a final position and a resolution.

"It may be necessary to take further action and the General Grades Committee has decided that this would take place between Tuesday September 8 and Thursday September 10. I will write to you again to provide further details nearer the time.

"I have advised LU that any movement towards the implementation of Night Tube, including running any test trains for Night Tube, will lead to us calling further industrial action without delay. Likewise, if our reasonable and just demands to protect the jobs and terms and conditions of Station Staff are not met, this will also lead to us calling further industrial action without delay."

And TSSA leader Manuel Cortes said: "I am extremely pleased to say that our negotiating team has made sufficient progress to suspend this week's planned strike action on the Tube.

"However, we are not out of the woods yet. A number of issues need to be resolved before our dispute is finally settled.

"We will therefore announce future strike dates in due course although we remain hopeful that further talks will soon result in a negotiated settlement."

A planned strike by City Cruises - which offers transport on the River Thames - is still set to go ahead on Thursday this week.