UPDATE 1-Vattenfall says CEO Loseth to start before summer 10

* Oystein Loseth appointed new CEO

* New CEO to start before next summer

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STOCKHOLM, Nov 16 (Reuters) - Swedish power producer Vattenfall said on Monday it had appointed a new chief executive to replace Lars Josefsson, who has been heavily criticised in recent weeks in the Swedish media for poor management.

State-owned Vattenfall said Oystein Loseth would take over as CEO before summer of 2010 when Josefsson will retire.

Loseth is currently CEO of Dutch company Nuon Energy, which is 49 percent owned by Vattenfall.

In recent days Swedish media have rounded on Josefsson for a plan to sell the company's power grid and for a contract with Vattenfall's German subsidiary which makes the parent firm liable for nuclear accidents.

Vattenfall's owners, the Swedish government, weighed in last week with Enterprise Minister Maud Olofsson saying that the issues had not been handled well by the company and that the brand had taken a "big blow".

Over the last two years, Vattenfall has also been plagued with problems at its nuclear power plants in Sweden and Germany and speculation has been mounting that Josefsson would have to fall on his sword.