Npower is the brand name of RWE's UK electricity retail business and it also owns Innogy, formerly Npower Renewables, which is a major wind-generation player in Britain.
Reports in the UK press suggest that Goldman Sachs have been hired by RWE to look at sale options of elements of Npower, valued at up to £5 billion (€5.5 billion). Last year, Npower's retail business made profits of £245 million on revenues of £7 billion.
Iberdrola, the Spanish energy group — which also owns the UK's Scottish Power — has been tipped by some market analysts as a possible bidder for the Npower business.
RWE Npower said it did not comment on market speculation.