Australia’s trade minister has welcomed high-level confirmation from Beijing that there is no ban on coal exports, but has raised concern about slow processing times through some of China’s ports.

Simon Birmingham told Sky News on Sunday coal was currently taking twice as long as normal to clear ports in China, and he referenced a similar set of circumstances that impacted Australian coal shipments last year.

Birmingham characterised the current conditions as a “temporary blowout” in processing times and he noted the coal held up last year in Chinese ports had now reached its customers.

“All of this played out in the final quarter of last year and yet at the end of that quarter, when we reconciled all of the figures, exports to China were at record levels both by volume and by value,” he said.

Concerns that China had imposed an import ban flared late last week after a Reuters report said five harbours overseen by Dalian customs – Dalian, Bayuquan, Panjin, Dandong and Beiliang – would no longer allow Australian coal to be cleared. The report cited an unnamed official as the source of the information.

Given coal is Australia’s biggest export earner, the news from Reuters sent the Australian dollar tumbling, and senior government figures in Canberra scrambling to ascertain the truth of the report.

Late on Friday a spokesman from the ministry of foreign affairs in China said the Reuters report was untrue.

But while saying the import ban was incorrect, the spokesman confirmed Chinese customs was currently conducting quality and safety risk analysis and monitoring of imported coal because “some imported coal failed to meet the environmental protection standards”.

The foreign ministry spokesman said the purpose of the testing was “to better protect the legitimate interests and rights of Chinese importers and the environmental safety”.

Birmingham said on Sunday the Australia/China relationship was on a constructive footing, and he said he had conveyed to Chinese officials the importance of keeping coal moving through the ports. “This isn’t just important for Australian businesses, it’s important for the Chinese businesses which rely on this product,” the trade minister said.

The trade minister said he would continue to pursue the issue “privately and cooperatively” with Chinese officials, and Australia was “eager” to understand any reasons for the delays.

He said “in the main” the chief executives of Australia’s major resources companies were calm about the port processes, and the minister said it was reasonable for China to check the quality of coal imports – a circumstance he suggested would be beneficial to Australian product.

Birmingham’s comments came as the prime minister, Scott Morrison, spent Sunday on the hustings, unveiling a city deal for Hobart worth $1.43bn over 10 years and new drought support for Gippsland.

The Labor leader, Bill Shorten, also unveiled a new commitment to create a strategic shipping fleet during a speech in Melbourne.