HONG KONG (Reuters) - Hutchison Whampoa Ltd (>> Hutchison Whampoa Limited) said it plans to sell a one-third stake in its British mobile phone business for $4.3 billion to five investors - a move that will help the Hong Kong ports-to-telecoms group fund its boldest bet in Europe yet.

Hutchison, owned by billionaire Li Ka-shing, agreed in January to buy Telefonica's (>> Telefonica SA) British mobile unit O2 for nearly $15.4 billion and merge it with its UK subsidiary to create the top mobile operator in the country.

Singapore's GIC Pte [GIC.UL] and the Canada Pension Plan Investment Board both said they will each pour 1.1 billion pounds ($1.7 billion) into the deal.

The other investors are the Abu Dhabi Investment Authority, Brazilian investment bank Grupo BTG Pactual SA (>> Grupo BTG Pactual) and Caisse de depot et placement du Quebec, which manages public and private sector pension funds and insurance funds, Hutchison said in a securities filing. Their investments were not disclosed.

The deal value could grow by nearly $500 million if the O2 mobile phone business meets performance targets, Hutchison added.

The Hong Kong conglomerate took on a 6 billion pound bank loan to finance the purchase of the O2 UK business and had flagged that it was talking with private equity firms and other investors for a minority stake in the business.

Hutchison's shares were up 2.1 percent in early morning trade, compared with a 0.8 percent gain in the benchmark Hang Seng index <.HSI>.

(Additional reporting by Rujun Shen in Singapore; Editing by Edwina Gibbs)

By Elzio Barreto

Stocks treated in this article : Telefonica SA, Hutchison Whampoa Limited, Grupo BTG Pactual