The Trade Development Council on Thursday more than doubled its forecast for export growth for the year, predicting that outbound shipments will rise between 7 and 9 percent, up from its 3 percent initial estimate.

This came as its latest survey in the so-called Export Confidence Index, a gauge measuring the city's foreign trade performances, crawled back above a key 50-point level in the third quarter to reach its highest level in seven quarters.

The index covers two major gauges, with the one tracking current performance standing at 53.3, up from 49.6 in the April-to-June period, while the other, tracking expectations for the next quarter, jumped to 54.3 from 49.

The increases reflected growing optimism among exporters, who adopted a front-loading strategy to rush shipments out ahead of US tariff changes, and as global trade tensions slightly eased, according to the council's director of research, Irina Fan.

"It's mainly due to the very strong increase in sales as well as new orders, which also trigger procurement activities," she told RTHK.

"But we have to be very cautious because we understand that starting from August, the US has already imposed relatively high tariffs on most of its major trading partners, which are also our major trading partners as well.

"And the China-US trade talks remain ongoing, so risks remain, and we could be subject to higher tariffs in the future."

Fan also warned that the latest ruling by a US appeals court added another layer of uncertainty to global trade, after it ruled that most of US President Donald Trump's tariffs were illegal, although it allowed the tariffs to remain in place until mid-October to give the White House the opportunity to appeal to the Supreme Court, which it did on Wednesday.

Trump earlier used the International Emergency Economic Powers Act (IEEPA) to impose steep levies on trading partners by declaring the US federal deficit with other nations as a national emergency.

Fan warned that the Trump administration's tariffs could still be around for the long term.

"We [understand] that currently the Trump administration tried to impose the tariffs under the IEEPA, but it doesn't mean that they cannot use other frameworks to increase the tariffs," she said.

"There are still other ways they could use to impose higher tariffs, but it might take more lengthy and complicated procedures."

She forecast that Hong Kong's export growth rate could slow to the low single digit in the coming months as the front-loading effects fade after it had risen by 12.7 percent in the first seven months of the year.

Fan noted that the city could continue to explore other key markets such as Asean, Europe and the mainland.