Amazon representatives fronted a Senate Select Committee into Work and Care in Sydney on Monday.

The committee was looking into job security, hours, rosters and the impacts on workers with caring responsibilities.

Committee member Labor senator Linda White raised concerns over the conditions of workers procured from labour-hire firms.

Ms White accused Amazon of having a "try before you buy" attitude after hearing Amazon hired a "vast majority" of its permanent workers through agencies.

The concerns came after hearing that non-direct Amazon workers were paid less than those directly employed by the company.

Labour hire workers earned $28.80 an hour, less than direct employees who got $30.17 an hour, plus benefits

"I'm just questioning why you have that high standard for your own direct employees but you don't have for anybody else procured elsewhere," Ms White said.

"What I was trying to establish is, is that your best employer on planet mantra to your own employees doesn't extend to anybody who is not directly employed."

Amazon outlined its company aspirations to be "Earth's best employer" while telling the committee about worker conditions.

The company stated it directly employed 6000 people in Australia, including 2200 people in its retail and fulfilment teams.

It has another 1300 workers in peak times procured mainly from labour hire company Adecco.

Amazon operations director Mindy Espidio-Garcia told the committee the company "expects our labour agency companies to comply with all legal obligations that are set against them".

"We want to continue to offer a range of options for employees and so they have the opportunity to take a look at what makes the most sense for them," she said.

"And our fulfilment centre rolls which you got to see today offer upskilling and in house training just for that purpose.

"We'll continue to invest in women as well."