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.
More top news
The attack on a college in Garissa, Kenya, comes a day after President Uhuru Kenyatta declared: ''Kenya is safe".
The pre-trial hearing for a British banker, accused of murdering two women in Hong Kong last November, was adjourned for five weeks.
Conservationists say one of the UK's most threatened butterflies has recorded its best year for a decade following 2014's warm spring.