Trading in shares of the Coles group has been halted after Perth-based diversified industrial company Wesfarmers announced it had bought a significant stake in the company.

Wesfarmers has confirmed it has asked for a meeting with the Coles board amid speculation that it could be about to launch a $20 billion takeover bid.

Wesfarmers made its move after the market closed late yesterday, snapping up large parcels of shares in the under-performing retail giant.

Wesfarmers says it now has voting power over 11.3 per cent of the retailer's shares.

About half of those shares have come from the investment company led by former Coles board member Solomon Lew.

Mr Lew's Premier Investments says it will sell its entire shareholding for $16.47 per share, valuing the stake at about $1.16 billion.

Wesfarmers is believed to be keen on securing Coles' Officeworks business, and may be working with a private equity consortium on a $20 billion takeover of the languishing retail giant.