Hong Kong billionaire Li Ka-shing's conglomerate Hutchison Whampoa has reported a more than doubling of net profit for the first half of the year.

Net profit rose to HK$28.44 billion ($3.67bn) for the first six months of 2014, up 129% from HK$12.4 billion in the same period last year, the company said.

It was buoyed by a one-off gain from the listing of electricity assets and growth in areas including infrastructure and telecommunications.

Hutchinson Whampoa owns the Three network in Ireland, which recently acquired its rival O2 Ireland.

The conglomerate's revenue, spanning ports to telecoms and financial services, amounted to HK$204.49 billion, rising 3% from HK$199.08 billion.

Li Ka-shing, Asia's richest man, warned in his outlook that economic and political uncertainty could become challenges for the rest of the year. 

"The Group will adhere to its fundamental principle of always acting in the best long-term interest of its shareholders," he said in a filing to the city's bourse website. 

Li's Power Assets spun off its electricity division in Hong Kong in January through an initial public offering. 

The listing made gains worth HK$16.07bn. Without the divestment benefits, Hutchison Whampoa's profits grew by 13%.

The group also sold part of its retail flagship AS Watson Holdings to Singapore's Temasek.

Li commands a vast empire through Cheung Kong Holdings and Hutchison Whampoa, with global assets in property, telecoms, utilities, ports and retail.

Despite the divestments, the 86-year-old has insisted there are no plans to reduce investments in the former British colony where he started his business career as a plastic flower-maker. 

His property flagship Cheung Kong Holdings said in a separate filing that its net profit for the first six months grew by 59% to HK$21.35bn. 

The growth came despite government measures to clamp down on red-hot property prices, including extra stamp duties on some purchases as well as taxing overseas buyers.