The Seattle-based company said the increase, which will take effect from 28 April, were subject to change and applied to clothing and non-clothing items.
The move follows an increase in fees announced in November, which came into effect in January.
Amazon did not immediately respond to a request for further details. But in a notice sent to sellers on Wednesday, the company said its costs had gone up since the beginning of the Covid-19 pandemic due to increases in hourly wages, the hiring of workers and construction of more warehouses.
Federal data released on Tuesday showed annual US inflation jumped to 8.5% in March, its fastest pace in more than 40 years. Petrol prices have rocketed 48% in the past 12 months.
Though the company blames inflation and rising fuel costs for the surcharge, Stacy Mitchell, a co-director of the anti-monopoly group Institute for Local Self-Reliance, said Amazon was taking advantage of the moment.
Amazon is also expected to release its earnings report for the first three months of this year on 28 April.
The company has long faced accusations of undercutting merchants that sell on its platform by making knock-offs, or very similar products, and boosting their presence on the site.
