The former Coalition frontbencher Stuart Robert breached security protocols by taking his work phone with him on a personal trip to China, Labor says.

In 2014, when he was the assistant defence minister, Robert travelled to China to oversee a mining deal with a Liberal party donor with whom he had business connections. While there, he met the Chinese vice-minister of land and resources.

On Sunday the Herald Sun revealed Robert had taken his work mobile phone with him on the trip.

The shadow attorney general, Mark Dreyfus, said the move could have posed a security risk, and said the federal police should investigate.

“What’s extraordinary is that in breach of absolutely clear instructions, that are given to all ministers, that they are not to take their government phones into China, Stuart Robert as assistant defence minister has done just that,” he told Sky News on Monday. “There’s a reason why there is this instruction that phones are not to be taken into China. A real security breach has occurred here and I think it warrants further investigation.”

The Department of Defence information security manual urges travelling members to take extra precautions. “When personnel leave Australian borders they also leave behind any expectations of privacy,” it says.

The document recommends a number of steps be taken before, during and after an overseas trip to protect the integrity of devices and the data they contain.

The recommendations include removing non-essential apps and data, enabling multi-factor authentication, effecting encryption on the device and avoiding using Wi-Fi or untrusted networks while overseas.

Guardian Australia has contacted Robert’s office to ask if the advice was heeded.

According to documents revealed to the Herald Sun under freedom of information, Robert’s phone was switched on and connected to Chinese or Hong Kong networks 12 times in two days.

“It was never used,” he said in a written statement. “It was turned on for the first 24 hours (until clearly I turned it off) and 61c ($0.61) was expended on the operating system connecting for checks (as every phone does). No data was received by the phone.”

In February Dreyfus referred the matter to the federal police for investigation, after an inquiry by the secretary of the Department of Prime Minister and Cabinet, Martin Parkinson.

Robert lost his place in the ministry over the trip, which he said was taken in a private capacity. He was the assistant defence minister under Tony Abbott and took on the human services and veterans’ affairs portfolios under Malcolm Turnbull.

