Imports at the US's biggest retail container ports are expected to continue to rise as the year goes on, despite new tariffs on goods from China, according to new data.

Figures from the National Retail Federation (NRF) and Hackett Associates' Global Port Tracker report show that the 12 major ports handled 1.82 million twenty-foot equivalent units (TEUs) in May.

This was up by 11.6 per cent compared to April and 4.3 per cent year-on-year. Meanwhile, June is estimated to hit 1.83 million TEUs and the figures for July and August are projected as being 1.87 million and 1.91 million TEUs respectively.

The trend was attributed to demand for summer merchandise, as well as retailers being unable to quickly change their global supply chains based on tariff alterations.

"As tariffs begin to hit imported consumer goods or the parts and equipment needed to produce U.S. goods, these hidden taxes will mean higher prices for Americans rather than significant changes to international trade," said NRF spokesperson Jonathan Gold.

Earlier this year, trade data showed that the US reduced its trade deficit in March following a rise in exports of goods and services and a decrease in imports.