* Chinese duties up to 16 pct, Russia up to 26 pct

* Duties back-dated to mid-December

* Investigation due to conclude in August (Adds investigation deadlines, EU industry complaint)

BRUSSELS, Jan 28 (Reuters) - The European Union will impose duties on imports of cold-rolled flat steel from China and Russia while its investigation into alleged dumping by the two countries continues.

The European Commission has set provisional duties of up to 16 percent for China and of up to 26 percent for Russia, according to sources familiar with the Commission’s plans.

The Commission’s investigation follows a complaint from Eurofer, the European steel association, which said Russia and China were dumping the steel - selling it below market prices at home or below the cost of production - on the EU market and thereby damaging the local industry.

The provisional measures are due to be announced by Feb. 14 and definitive duties, if imposed at the conclusion of the investigation, by Aug. 12. Such duties would typically apply for five years.

The Commission previously ordered customs authorities to register imports of cold-rolled flat steel from mid-December, meaning duties would apply to imports from China and Russia from then.

Eurofer says that, since the investigation was launched in May, imports of steel - used in cars and home appliances - into the EU have increased.

It said on Wednesday that overall imports of steel surged by 29 percent year-on-year in the third quarter of last year and by 51 percent in the final three months.

Russia, China and Ukraine made up some 60 percent of total steel imports.

For cold-rolled flat steel, Eurofer has said the average dumping margin - the amount by which export prices from the two countries undercut a normal market price - is 28 percent for China and 15-20 percent for Russian producers.

Russian producers Severstal and Novolipetsk Steel said when the investigation was launched last May that they were in compliance with international trade rules and not carrying out dumping.

China said then that the surge in Chinese steel product exports was “normal and also beyond reproach”, reflecting a rise of demand and the strong competitiveness of its industry. (Reporting by Philip Blenkinsop; Editing by Robert-Jan Bartunek and Mark Potter)