The U.K. antitrust regulator said Friday it will review the ownership of the country's infrastructure assets, including ports, airports and energy and water networks, so it can map who owns what and decide whether it raises any antitrust or consumer issues.

Many of the U.K.'s infrastructure assets are owned by foreign firms or infrastructure funds after being privatized in the 1980's and 1990's and many have changed hands over the past decade.

For example, Spain's Grupo Ferrovial SA (FER.MC) owns the country's biggest airport operator, while Dubai's DP World (DPW.DIF) and Singapore's Hutchison Whampoa Ltd. (0013.HK) are major port owners. The U.K.'s energy infrastructure is owned by a mix of utilities and private investors, according to regulators and companies.

"The stock-take is intended to improve public understanding of competition issues in U.K. infrastructure markets. It may also lead to further work by the OFT if specific competition or consumer issues are identified in any of the sectors," the Office of Fair Trading said.

It expects the stock take to be completed in the fall, and interested parties can make submissions to the regulator.

"There have been significant changes in ownership of infrastructure assets in both regulated and unregulated sectors of the economy over the past decade. We want to take this opportunity to step back and assess how these developments might have affected competition and consumers," said Heather Clayton, senior director of the OFT's infrastructure group.

The U.K.'s airports are owned by a mix of Ferrovial's BAA airports group, local authorities and private partnerships, and infrastructure funds. BAA has already been forced to sell two of seven airports after a previous antitrust probe into the company found it was too dominant BAA declined to comment on the OFT's review.

The U.K.'s energy network could face scrutiny due to its complicated system of interaction between major network operators, smaller grid operators and the utility companies which provide energy to consumers.

National Grid PLC (NG.LN) owns the high-voltage electricity networks in England and Wales. The high-voltage lines carry power to 14 low-voltage distribution networks, which conduct power to consumers.

The 14 networks are controlled by EDF Energy, a unit of Electricite de France (EDF.FR); CE Electric, a subsidiary of Iowa-based MidAmerican Energy Holdings Company; Central Networks, a unit of Germany's E.ON AG (EOAN.XE); ScottishPower, a unit of Spain's Iberdrola SA (IBE.MC); London-listed Scottish & Southern Energy PLC (SSE.LN); privately held Electricity North West Ltd.; and Western Power Distribution, a subsidiary of Pennsylvania-based PPL Corp. (PPL).

EDF is in the process of selling its network to reduce debt. Bidders include Hong-Kong's Cheung Kong Infrastructure Holdings Ltd. (1038.HK); sovereign-wealth fund Abu Dhabi Investment Authority, Macquarie Capital and Canada Pension Plan; and U.K. utility Scottish & Southern Energy along with Canadian infrastructure fund Borealis.

ScottishPower owns high voltage networks and low-voltage distribution lines in southern Scotland, while Scottish & Southern holds similar interests in northern Scotland.

For natural gas, National Grid controls the U.K's National Transmission System--more than 6,600 km of pipeline which supplies gas to 40 power stations, a handful of large industrial consumers and 12 local distribution zones.

National Grid, privately held Wales and West Utilities, and Northern Gas Networks, majority owned by Cheung Kong Infrastructure and Hong Kong Electric Holdings Ltd. (0006.HK), own different distribution zones.

Unlike the electricity sector, there is only limited competition in the water sector. Regional monopolies control the supply and there is no national water supply network in England and Wales, with only a few interconnections between regional monopolies.

One of the main reasons for this is that unlike electricity and gas, water is very costly to transport from one area to another.

Last year the U.K. government sponsored the Cave review to see if markets could play a greater role in the water sector. The review made a number of recommendations, including giving more business customers a wider choice of supplier and a recommendation to open up the retail divisions of the water companies to more competition.

There are 10 major water and sewage companies and an additional 12 companies providing water only. They are a mix of U.K.-based and foreign companies, including utilities, private investors and infrastructure funds.

-By Steve McGrath, Dow Jones Newswires; 44-20-7842-9284; steve.mcgrath@dowjones.com

(Kaveri Niththyananthan contributed to this article.)