 Many Tube users turned to the buses during last month's strike |
Informal talks have been held between the union behind last month's Tube strike and London Underground bosses. The Rail, Maritime and Transport (RMT) union has rejected a 3.5% pay offer and is concerned about changes which it fears could lead to job losses.
Its executive will meet next week to decide on its next move.
A 24-hour walkout by RMT members crippled most of the Tube network at the end of June after negotiations broke down.
About 1,000 extra buses took to the roads to cope with the millions of Tube users whose journeys were disrupted.
Bobby Law, the RMT's London organiser, told BBC London: "We've had some very constructive talks with London Underground this week which we believe may progress our claim for a four-day week for our members and also to bring in a 35-hour week without the strings of 800 job cuts which were previously on the agenda.
"We are hoping these talks continue and we are hoping to move forward on that."
LU previously described the RMT's demands for a four-day week as "not affordable".