China could order dozens of Airbus jetliners during a visit by Premier Wen Jiabao to Berlin according to sources, but the deals are clouded by a spat between Beijing and Europe over aviation carbon tariffs.

A Chinese leasing firm could, under one scenario discussed in the build-up to the visit on Tuesday, order over 60 A320 aircraft, worth about $5 billion at list prices, according to sources close to the negotiations.

But other people familiar with the matter said the type and value of deals had not yet been finalized on the eve of the visit.

Airbus declined to comment.

Britain and China signed a series of deals worth $2.3 billion during the premier's visit there on Monday.

The visit comes just days after industry sources said China had delayed the announcement of a $3.8 billion order for 10 Airbus A380 superjumbo jets at the Paris Air Show to protest over EU emissions trading rules.

Under plans to include international aviation in its carbon market from next year, the EU would require all airlines flying to Europe to buy permits for each tonne of carbon dioxide they emit above a certain cap.

Air transport body IATA has called the proposed scheme illegal and industry players, including German airline Lufthansa , say China has threatened retaliatory measures if the EU pushes through its plans.

But while China continues to put the brakes on lucrative orders of European wide-body aircraft, this week's visit will demonstrate whether the row has spilled over to narrowbody A320 aircraft which China helps assemble to feed huge traffic growth.

Although it plans to start competing with Airbus and Boeing by building its own narrowbody passenger jets from the second half of this decade, China continues to order large volumes of Airbus A320s and Boeing 737s to support its economic growth.

Such narrowbody airplanes seat about 150-160 passengers.

Airbus began assembling A320s for the Chinese market at a factory in Tianjin outside Beijing in 2009.

China typically schedules aircraft orders to coincide with political visits, but the deals are often difficult to analyze as to whether the contracts are new or not. (Reporting by Rene Wagner in Berlin and Tim Hepher in Paris; Writing by Victoria Bryan)