Thousands of US government officials have unlimited access to as many as 10,000 devices which are seized from travelers moving across the country.  

Electronic devices such as cellphones, iPads and laptops taken from those going through airports, seaports and border crossings are being mined for data. 

The leader of the Customs and Border Protection told congressional staff that the massive database can be accessed by 2,700 CBP officers without a warrant.

During a briefing, which took place in the summer, officials also said that the data is maintained for 15 years.

It has raised alarms in Congress about what the government is using the information or, with many of the devices taken from people not suspected of any criminal activity.

Details of the database were revealed on Thursday in a letter from Senator Ron Wyden to CBP Commissioner Chris Magnus.

He criticised the agency for 'allowing indiscriminate rifling through Americans' private records' and called for stronger privacy protections.

Senator Paul and Wyden introduced a bill last year which required border officials to get a warrant before searching a device.

Currently the CBP have the authority to conduct a 'basic search', which includes looking and scrolling through the device.

Anyone who refuses to unlock their phone for the process can have it confiscated for up to five days.