The other is state owned Jaya Container Terminal (JCT), the port's main transshipment facility, has seen a slowdown in volumes.
Colombo port's total container handling in September, the latest month for which figures are available, were down 4.
7 percent to 319,818 TEUs from a year ago.
The JCT, which handles much of the island's export and import boxes, was hurt by a sharp contraction in trade, as demand for exports and imports were reduced by a recessions.
Colombo is South Asia's main hub port, where cargo is shipped on feeder vessels to and from smaller ports in the.
Volumes at SAGT were up 1.4 percent to a new annual high of 1,749,796 TEUs (twenty foot equivalent units or containers), analysts said.
Volumes rose 26.5 percent in December to 155,691 TEUs from a year earlier.
It was also higher than the November volumes of 153,793 TEUs.
Total volumes at SAGT have largely been growing this year, although domestic import/export volumes have been hit by a slump in trade due t