Adecco SA, the world's largest staffing firm, must submit a bid for Michael Page International PLC by 5 p.m. on Sept. 30 or announce it won't make an offer. The deadline was set by The Takeover Panel, an organization that regulates takeover bids and merger transactions in the United Kingdom.

Earlier this month, London-based professional staffing firm Michael Page ended talks with Adecco about a possible acquisition saying a proposal by Adecco undervalued the company. However, Adecco said it was weighing another offer.

The Adecco proposal valued Michael Page shares at around 400 pence each. Under the deal, Michael Page would issue new shares to Adecco to give it at least a 50.1% stake in the firm. Michael Page's British shareholders would receive around 200 British pence per share in cash in return for their shares being diluted.