Border Force has seized more than 1,000 devices from people entering Australia in past five years

Border Force officers have seized or retained more than 1,000 devices from travellers entering Australia in the past five years but the agency cannot say how many of those interventions led to criminal prosecutions, prompting human rights experts to question the appropriateness of the powers.

The last two years likely reflect the significant drop in international travellers arriving in Australia as a result of border closures during the Covid-19 pandemic.

Figures obtained by Guardian Australia reveal Border Force keeps roughly one in every 40 devices searched at the border. This comes after data released last month showed officers had searched phones, computers and other devices at the border 41,410 times between 2017 and the end of 2021.

The practice has been shrouded in mystery, with information on its operation having to be extracted from the department through formal freedom of information and parliamentary processes in the past few months.

There is no limit on how long the devices can be held, but the agency said the policy was to keep devices for no longer than 14 days unless it would take longer to examine them.

The agency also revealed this week that based on records since May 2020 on whether a copy of the device had been made after searching, 34 devices were copied between May and December 2020, and 270 were copied in 2021.

Data prior to May 2020 was not available due to it not being in a searchable format.

Border Force also has no records available for how many criminal charges or other legal action have arisen from data obtained through phone searches at the border.

Digital and human rights groups have called for more transparency and safeguards over the use of the power at the border.

Justin Warren, the chair of Electronic Frontiers Australia, said it was a surprising admission for the agency to say it had no records of prosecution, and said the power to search devices without a warrant should be removed.