Prime Minister Scott Morrison has warned against linking processing delays of coal exports to China with diplomatic tensions, as Australia seeks answers about the slowdown.

Coal export unloading times have almost doubled to 40 days, but the federal government has dismissed suggestions a ban has been in place a the northern port of Dalian.

Mr Morrison urged caution around how the delays were characterised, after speculation a possible ban was retaliation for Chinese telecommunications company Huawei being banned from the 5G mobile rollout.

‘I think the great risk of that is it will cause needless anxiety and concern particularly in our mining and resources sector,’ he told reporters in Hobart on Sunday.

He said leaping to conclusions was unhelpful and unwarranted.

‘From time to time there have been decisions made in local ports,’ Mr Morrison said.

‘We’re talking about ports here which actually represent a very small portion of our coal exports to China.’

Trade Minister Simon Birmingham confirmed he was seeking an explanation why processing times had blown out from about 25 to 40 days at some ports.

‘There remains some issues around the timeliness of processing through ports and we’re eager to understand any reasons for some of those delays,’ he told Sky News.

Labor leader Bill Shorten said he didn’t want to rush into blaming China for the delays.

‘There’s a lot of China bashing that goes on in parts of our political debate,’ he told reporters in Melbourne.

‘If there is a government policy, we need to get to the bottom of it and stop it and change it, but I don’t want to start jeopardising our trade by making hysterical, headline-hunting gestures.’

Senator Birmingham said a similar situation occurred in the final quarter of last year, but Australian coal exports remained at record levels.

In 2018, Australia exported 89 million tonnes of coal to China, worth $15 billion, just shy of a quarter of the country’s total coal exports.

Australia’s ties with China have been rocky at times since 2017 when Canberra accused China of meddling in its domestic affairs.

Tensions rose again last month after Australia rescinded the visa of a prominent Chinese businessman, just months after the Huawei ban.

Senator Birmingham said he had good relations with his Chinese counterpart.

‘We don’t swap text messages full of emojis but we do absolutely make sure we have professional lines of communication,’ the trade minister said.