China's Nio said on Tuesday it would launch its Firefly electric vehicle in Europe in the third quarter, later than initially forecast, after it underestimated challenges involved in sales and service network expansions in the region.

The company unveiled the Firefly brand in December as a rival product to Mercedes-Benz's Smart and BMW's Mini and said at the time it would launch it in Europe in the first half of this year.

Nio's progress in Europe has been slower than expected due to the sales and service network challenges, Nio CEO William Li told reporters at an event ahead of the Shanghai auto show.

Nio plans to seek more local partners to expand in Europe and will announce some deal signings with European partners during the show, he added.

The company originally conceived Firefly as a brand that would boost its market share in Europe, but the European Commission in October imposed tariffs on Chinese-made EVs sold in the EU.