0808 GMT - Bitcoin retreats, staying below the key $80,000 level after briefly climbing to a 3-month high of 81,326.81 overnight. Demand for bitcoin has been rising as investors seek alternative investment opportunities to the U.S. dollar following the recent announcement by the Treasury about doubling buybacks of long-dated U.S. government bonds. However, it has failed to sustain any gains above $80,000, with profit-taking quickly setting in above that level. Bitcoin falls 0.4% to 79,741.00, LSEG data show.