The Australian Retailers Association, which represents more than 50,000 shopfronts, on Monday urged shoppers to plan early to avoid disappointment.

Australian Retailers Association chief executive Paul Zahra said tightened Covid restrictions in China and the temporary closure of one of the world’s busiest ports has prompted deep concern about the further impact on global supply chains.

“Supply chain issues have been an ongoing concern for Australian retailers throughout the pandemic and it’s likely to be compounded by these latest developments, in particular as the busy Christmas shopping season approaches,” Mr Zahra said.

Retailers had reported the capping of incoming flights had put significant strain on shipping, he said.

At the same time, container costs had escalated up to four times their usual rate, a factor likely to have a flow-on impact on retail prices.

Mr Zahra warned shoppers to plan ahead in light of the situation.

“The key message for consumers is don’t leave your Christmas shopping till the last minute,” he said.

“If you’re purchasing items online, give plenty of time for your product to be shipped and delivered to avoid disappointment.”

Discount chain The Reject Shop, which has more than 350 stores nationally, said it took an unexpected $9m hit from international shipping costs for the 2021 financial year.

Costs would likely remain high for the rest of the year, the company said earlier this month.

“Unlike in FY21, these higher international supply chain costs have been factored into management’s budget in FY22; however, they continue to increase each month,” the retailer said.

Some retailers have boosted their stock levels in anticipation of short supply.

Electronics seller JB Hi-Fi Limited, which takes in JB Hi-Fi and The Good Guys, revealed this month it had built up a big product stockpile after being hit by Covid-related shortages last year.

Inventory at the end of June amounted to $938.8m worth of stock, up $199.5m.