Mr Gore, who is holding talks with Russia's Prime Minister, Viktor Chernomydrin, outside Moscow, drew a distinction between long-term US-Russian space co-operation and the American commitment to the 11-year-old Mir.
"We will make a careful evaluation whether to proceed with the seventh shuttle-Mir docking," he said.
"Any decision to move forward will be based solely on mission safety. This is a very old space station."
Mr Gore's cautious statement contrasted sharply with remarks by Mr Chernomydrin, who has regularly met the American Vice-President to discuss bilateral co-operation on space and technology. "There are no problems for the continuation of joint Russian-American experiments on the Russian space station," he said.
Mr Gore has been a leading proponent of US-Russian cooperation in space. But the string of technical failures this year has inflamed criticism in Washington, which has bankrolled much of Mir's expenses in recent years.
Yesterday the ageing space station suffered from several new problems. The central computer went down again and a mysterious brown cloud appeared outside the craft itself.
Cosmonauts noticed a the brown substance, or drops leaking from the station, which they could not identify. Russian space officials were also unsure what to make of the reports of the brown substance of unknown origin.
"We have another observation which we do not understand at all. When we were monitoring the turning of the ship we saw some brown drops coming from it," Mir's commander Anatoly Solovyov said in a radio exchange.
The Flight engineer Pavel Vinogradov said they noticed the drops when they fired the engines of the Soyuz escape capsule to turn the station round, so that its solar panels could absorb more energy.
"The drops were fanning outwards for a long time and then stopped. They were a brown colour," he said.
The computer failure disabled Mir's automatic orientation system, which points the station at the Sun for its solar panels to soak up maximum energy. As a result, the crew spent part of the day in darkness with major systems shut down to save power.
Later yesterday the crew was reported to have repaired the space station's computer. The crew had not, however, restarted the system that removes carbon dioxide from the station. The deputy flight director Viktor Blagov said the problem was relatively easy to rectify and the crew could survive 26 days without the system.
The US space shuttle Atlantis is due to blast off on Thursday with a relief cosmonaut, David Wolf, aboard. It is intended to dock with Mir three days later.Reuse content