CIMIC, Australia's biggest construction group, laid off dozens of workers at its Thiess mining services division and halted staff bonuses, heightening concerns that its cash flow is being squeezed as it tries to complete several multi-billion dollar projects.

CIMIC was due to pay Thiess staffers their 2019 bonuses, which can account for up to 25 per cent of their annual income, in late April, according to people familiar with the company.