Leader of the RMT Bob Crow said the tube strike will go ahead after talks between London Underground bosses and the union failed to reach an agreement over pensions.
He said: "The action next week remains on and it is the management's intransigence that is responsible for the disruption travellers can expect."
No further talks between leaders of the RailMaritime and Transport (RMT) union and London Underground leaders have beenarranged, raising the threat of disruption to Tube services next week.
Earlier this week RMT officials said its members will walk out at 4pm on Tuesday until the same time on Friday.
Talks aimed at averting strikes by London Underground maintenance workers next week in a row over pensions have ended without agreement, Acas said.