* Deal could grow by $500 mln to meet more Telefonica payments
* GIC, CPPIB to each invest 1.1 bln pounds
* Hutchison's shares rise 2.1 pct (Adds details of the transaction, GIC, CPPIB investments)
By Elzio Barreto
HONG KONG, May 8 (Reuters) - Hutchison Whampoa Ltd 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 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 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 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.
$1 = 0.6461 pounds Additional reporting by Rujun Shen in Singapore; Editing by Edwina Gibbs