Engineers examining why the cracks appeared in the Gotthard Road tunnel are exploring the possibility they could have been caused by the tunnelling for the second tunnel, which is due to open in 2029.
Work on the new tunnel has been suspended.
Last month the existing tunnel was closed briefly after slabs fell from the ceiling.
Experts told the SonntagsZeitung newspaper it may be necessary to increase the distance between the tunnels which would delay the planned opening.
Heat to stay for now
The heatwave alert has been extended until Thursday, with temperatures set to climb as high as 37 degrees in some areas.
Growing anger over World Cup red card
The Swiss team's manager, Murat Yakin has called Breel Embolo's red card 'unacceptable', as anger builds over the refereeing of Switzerland's World Cup quarter-final loss to Argentina.
Fire damages trees in the Jardin Anglais
A fire tore through part of Geneva's Jardin Anglais on Saturday morning, gutting several trees and damaging a lakeside building used by the Mouettes ferry service.
Cows sweltering in the heat
The heat is now hitting the country's dairy herds, with cows producing less milk as they burn extra energy to stay cool.
Lake Geneva nudists fight for their lake section
A hidden stretch of Lake Geneva shoreline has become the focus of a long-running battle over public nudity.
Holiday makers seek more than the sun
Nearly half of Swiss holidaymakers are choosing to learn a new skill on their summer break rather than simply lie on a beach.
