The confirmation of a tabloid experiment came two weeks after it was revealed exclusively in Marketing (November 13).
But Times Newspapers managing director Clive Milner said readers would decide whether The Times would go fully tabloid.
"We won't force it, but if the market wants it, then so be it," he said. "The Times already has eight tabloid sections, which no one would have imagined a few years ago."
Milner did not rule out the prospect that advertisers might be compensated for the reduction in page size.
"We are not operating a separate rate card, but we will come back to advertisers at the earliest opportunity to talk about the value we are offering. And we will take a view on that value when we have assessed performance," he added.
Earlier this month, Times Newspapers marketing director Andrew Mullins categorically denied a tabloid launch was imminent, saying that production scheduling difficulties at its printing plants ruled out such a move.
These difficulties have limited the initial tabloid print run to just 70,000 copies, on sale from this week. This figure is about 20,000 fewer than The Independent's initial distribution of its tabloid version within the M25.
Milner said distribution would be cranked up as soon as production schedules allowed, and would be extended into other major commuter belts across the UK.
The Times' move has caught its rivals on the back foot. The Daily Telegraph and The Guardian are both printed at West Ferry Printers, which is shared with the Express papers, and insiders say production capacities preclude any early response by either broadsheet.