LONDON, Feb 7 (Reuters) - Rebuilding its Chinese business after COVID-19 lockdowns will be a "long and tedious journey", Pandora's CEO said on Wednesday, while Carlsberg pledged to spend more on marketing to appeal to beer drinkers in the world's No. 2 economy.

The world's biggest jewellery maker and one of the world's top brewers struck a rather muted tone about the health of Chinese demand as the country heads into the Lunar New Year holiday, one of the busiest periods of the year.

Their comments highlight the continued challenge for companies selling everything from phones to cars and necklaces as Chinese consumers tighten their belts amid uncertain employment prospects, especially for younger people, a plunging stock market, and declining property values.

Those problems derailed expectations for a strong post-pandemic rebound last year.

"I think it's going to be a long and tedious journey," said Pandora CEO Alexander Lacik after fourth-quarter sales in China, the world's largest jewellery market, missed expectations.

"People ask me why do you bother, it's 2% of your revenue base. That's one way to look at it, but if you then say it's 1.4 billion people, it's the largest jewellery market in the world, then you get a different perspective," he said.

Carlsberg CEO Jacob Aarup-Andersen said he was "cautiously optimistic" that conditions there will stabilise over the year, which should also boost other economies in southeast Asia.

"There's no doubt that the Chinese market in 2024 will at least start in the same way that it ended (2023), which means a subdued consumer environment," he said on a call with media.

"We're not going to predict when that turns, but we are optimistic that we can continue to grow in that market."

As a result, the maker of brands such as Kronenbourg 1664 is stepping up its investments in China.

It plans to increase sales and marketing spend by over 10% in the coming year, with a large portion of that dedicated to China as well as other key Asian economies and its portfolio of more expensive beers.

Pandora's Lacik said early results after the company's relaunch in Shanghai in July last year were encouraging.

(Reporting by Helen Reid and Emma Rumney in London. Writing by Josephine Mason in London. Editing by Mark Potter)