MAAS Group Holdings' (ASX:MGH) proposed sale of its construction materials business to Heidelberg Materials Australia is under a phase one initial assessment by the Australian Competition and Consumer Commission (ACCC), the regulator said Thursday.

Maas Group agreed to sell the unit to Heidelberg in February for up to AU$1.7 billion in cash.

The ACCC said the two companies overlap in the supply of ready-mix concrete, coarse aggregates, fine aggregates, asphalt, and construction-related waste disposal and recycling services in certain regions in Australia.

The phase one review of the deal is expected to conclude by July 13.

The company's shares were up 1% in recent Friday trade.