Labor deputy leader Richard Marles says Australia's relationship with China is "terrible", accusing Prime Minister Scott Morrison of using "megaphone diplomacy" against the nation's largest trading partner.

Key points: Richard Marles says there is a sense in China that Australia is losing relevance

Richard Marles says there is a sense in China that Australia is losing relevance He says the trade tensions between the United States and China are causing anxiety inside Australia

He says the trade tensions between the United States and China are causing anxiety inside Australia Mr Marles says Australia should be focused on building trust with China

Mr Marles, Labor's defence spokesman, has just returned from a three-day study tour of Beijing.

"The state of the relationship as it exists between Australia and China right now is terrible," Mr Marles told ABC's Insiders.

"I think there is a sense in which we are falling down their ladder of relevance.

"China is not seeing us in the serious way in which it has seen us in the past."

Mr Marles took aim at Mr Morrison, who last week during a visit to the United States called for the superpower to no longer be considered a developing country and to face tougher trade obligations.

"There are trade tensions brewing between the United States and China, and those tensions are causing enormous anxiety for people in this country," Mr Marles said.

"And in that place (the United States), you know, essentially, wearing his baseball cap, [Morrison] takes pot shots at our largest trading partner.

"The context in which he has engaged in this megaphone diplomacy is absolutely the issue and it's not the way in which this issue should be dealt with in a respectful way."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 22 seconds 22 s While in the USA, Scott Morrison said China should no longer be considered a developing country.

Mr Marles said the past week had added to the "terribly" managed relationship between Australia and China, by the Coalition Government over the past six years.

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Mr Marles was joined by other MPs for the three-day tour, hosted by the Australian policy institute China Matters, aimed to help Australian officials better understand the country and the "complexities" of the relationship between the two nations.

Mr Marles said the focus should now be on building trust with the superpower, using the countries' "military-to-military" relationship as leverage to build on that.

"We already engage in activities with the Chinese military," Mr Marles said.

"So I'm not advocating that we do anything which puts us in a position of vulnerability, but there is a whole lot of scope here where we can engage in activities which help to build trust."

Mr Marles said he did raise human rights issues with Chinese officials during the visit, including the treatment of Uyghur Muslims minority in the western region of Xinjiang.

But he did not raise the case of Australian citizen Yang Hengjun who was formally arrested after spending seven months in detention on suspicion of spying.

"I didn't raise that specifically but the point here is that it is a complex situation where there is good and where there is bad," Mr Marles said.

"But ultimately, we have made a decision to engage. We made that decision back in 1972. We continue with that decision now."

Mr Marles has previously said Labor is deeply concerned by the detention of Dr Yang and called on the Chinese Government to clarify the reasons for his detention.