A report is due to go to ministers this month from High Speed 2, the firm established by the government to determine a suitable route from London to the West Midlands and options for extensions further north.
Adonis said the High Speed 2 report will not be published until the government issues its response in March to avoid planning blight. Full consultation would follow next autumn.
"The potential for high-speed rail to regenerate and reinvigorate is a reality for people in Kent. But the size of the UK's high-speed network lags behind that of many of our European neighbours and does not link any of our major cities," he said.
Meanwhile, Kent County Council has linked up with Nord-Pas de Calais, Breda, West Brabant and the BrabantStad urban network to lobby in Europe for a wider high-speed network.