trails seen by pilot over russian airspace too high to be aircraft.in an aircraft flying to london on airway A356 over southern russia between reporting points kzo(kyzylorda) and nk(novokazalinsk), speaking to kyzylorda control. saw an object which we thought was a shooting star to start with but then realised it could not be due to it lasting for 20-30 seconds and then it looked like it vapourised, it was seen at the 2 o clock posn, a bright object with a tailtravelling horizontally. at a distance of 50 miles(at a guess). we were at 35000 ft - ish. it must have been at at least 50 - 60000 ft maybe more. 5 mins later another object (or the same one) was seen at the 3 o clock posn bright with a tail again but moving away from us, this lasted over 2 minutes, during which time an excited controller turned all aircraft off the airway and would not explain the reason.i was wondering if this could be russian rocket research or a shuttle returning?