(ShareCast News) - Diageo has proposed to acquire an increased stake in Guinness Nigeria to 70% but maintain its listing on the Nigerian Stock Exchange.Guinness Nigeria confirmed an offer had been made by FTSE 100-listed Diageo to increase its equity stake from 54.3% up to a maximum of 70% at a maximum offer price of 175 Nigerian naira (NRN) per share.Diageo said, subject to receiving regulatory approval, its Guinness Overseas Limited subsidiary would launch a partial tender offer that would give all Guinness Nigeria shareholders the opportunity to sell some or all of their shares up to that maximum price.At 175 NRN per share, the offer would represent a premium of 36% to the 30-day volume weighted average share price and 40% to Guinness Nigeria's closing share price on Tuesday.The naira has lost 8.5% of its value since the start of the year after February's de facto devaluation following the slump in the price of oil, Nigeria's main export.Diageo, which added that it may also seek to acquire shares in the market at similar prices, stressed that the announcement did not constitute the announcement of an offer and created no obligation on Guinness Overseas or Diageo to make an offer.