Clifford Chance (CC), Allen & Overy (A&O) and Linklaters have ridden the wave of surging infrastructure investment in 2006 to dominate the top end of the global project finance market.

Research from Infrastructure Journal shows the three City firms dominating the global rankings for project finance in 2006, with CC topping the table after closing 34 deals with a combined value of $43.9bn (£22.3bn).

Linklaters is in second place, advising on deals worth $29.4bn (£14.9bn), with A&O's projects team taking third place in the value ranking after closing projects worth $28.9bn (£14.7bn).

However, A&O's much-vaunted projects team – traditionally a bellwether practice for the European projects community – secured a significant result after topping the volume rankings, closing a total of 44 ranked projects.

Other London firms to post strong results included Herbert Smith and Norton Rose, ranked eight and 10th respectively in the core global table.

Notable roles for CC in 2006 include the $3.3bn (£1.7bn) Allenby and Connaught Ministry of Defence accommodation project, the $1.3bn (£700m) Bahraini power project El Hidd and the $1.9bn (£900m) St Barts Hospital public-private partnership.

CC project finance partner Andrew Grenville said the firm's market share had been boosted by its drive to shape its practice around sectors, notably telecoms, transport and energy and utilities.

He added: "Our team reflects clients' requirements as those areas have specific issues regardless of the transaction and we try to broaden the repertoire of legal focus along industry sectors."

Projects partners cite the Middle East as continuing to be one of the most important regions, and the tables reveal that in 2006 it generated the second-largest deal value with $107bn (£54bn) of deals, second only to western Europe on $155m (£79bn).

CC tops both regions by value, although Linklaters and A&O are ahead on volume. In Africa and the Middle East, CC leads with seven deals worth $16.29bn (£8.3bn), with White & Case in second place with three deals worth $10.7bn (£5.4bn).

Grenville told Legal Week: "The integration of our global practices is reflected in the fact that we are acting in the Middle East, sub-Sahara and Asia; the whole global footprint is working well for us."

However, A&O projects chief Graham Vinter told Legal Week that North America, currently dominated by US firms Latham & Watkins, White & Case and Milbank Tweed Hadley & McCloy, is top of the magic circle firm's focus for the coming year.

"North America is slowly waking up," said Vinter. "They have huge projects, each one around half-a-billion dollars, and we want to be a part of that market."

The results once again bring to the fore the 'value versus volume' debate, with Grenville commenting: "Law firms have more of a focus on volume than a bank does, where value is everything, but both are important."

Latham finance partner Simon Dickins told Legal Week: "I tend to look at value because the larger deals tend to be more complicated; some projects work is becoming commoditised but the cutting-edge work tends to be bigger."

However, Vinter said: "Both are equally important but what matters is a strong deal book and good clients."

Infrastructure Journal's research also underlines the overall boost to the projects sector in 2006 with investors increasingly drawn to the solid returns of existing utility assets while governments continued to turn to the private sector for new-build projects.

Overall, the global value of ranked deals rose 35% against 2005, while the volume was up from 323 to 437. The research also underlined the emergence of the renewables sector as a generator of big-ticket projects work, with Linklaters highlighted as the most active adviser for renewable projects.

Linklaters client energy group head John Pickett commented: "The order book for 2007 is already good with offshore wind and solar looking particularly strong. Geographically, we expect increasing activity across our Central and Eastern European network."