The earlier high-pressure study of C₆₀ concentrated on the orientational transition and room-temperature transformations observed in diamond anvils. This work presents a part of the T-P phase diagram for solid C₆₀ at pressures up to 20 kbar in the temperature range extended to 700 K. A new phase region is outlined herein. The new phase is retained to ambient conditions and preliminarily characterized. The new phase is more dense than the initial C₆₀ by at least 8.5% and less compressible by approximately 1.5 times. Its crystal structure is very different from the well known face-centred cubic and simple cubic phases, and its recovery to a cubic phase is associated with an endothermal heat effect of approximately 23 J g^-1. The nature and the thermodynamic stability of the new phase are discussed in connection with polymerization of C₆₀ molecules, which seems likely.