Flashing lights on craft, motionless for extended period, followed by hight speed, erratic movement vertically and horizontally

On a flight from Lagos (Nigeria) to Amsterdam (Netherlands), i suddenly noticed flashing lights at a great distance from our aircraft at 36,000ft. I observed the flashing lights for approximately 10 mins to determine any movements that might identify this as another aircraft; the object however remained at a fixed and motionless point in the distance over the time. Suddenly, and without any visible trail or propulsion, the obect flashing lights began to move a significant distance both vertically and horizontally, in fractions of a second, in an erratic manner. I took out my mobile phone to record the object movements on maximum zoom video; the erratic movements continued for a further number of minutes. I looked at my phone to review the quality of video taken and looked up after 10-15 seconds, the object had vanished from view completely. There was no turbulence whatsoever at this point in the flight, and therefore no consequent notable aircraft movement during filming; camera hand movement was also very limited indeed. The skies were very clear, no cloud or other cover present. I made the following notes of location annd direction from aircraft flight data as follows: North East of Bir el Ater, equidistant from Batra to the left, heading towards Tebessa; 1181 miles from Amsterdam; time 03.10 GMT; altitude 10,973m, ground speed 854Km/h.