Context : The supernova remnant ( SNR ) W51C is a Galactic object located in a strongly inhomogeneous interstellar medium with signs of an interaction of the SNR blast wave with dense molecular gas .

Aims : Diffuse X-ray emission from the interior of the SNR can reveal element abundances in the different emission regions and shed light on the type of supernova ( SN ) explosion and its progenitor .
The hard X-ray emission helps to identify possible candidates for a pulsar formed in the SN explosion and for its pulsar wind nebula ( PWN ) .

Methods : We have analysed X-ray data obtained with XMM-Newton .
Spectral analyses in selected regions were performed .

Results : Ejecta emission in the bright western part of the SNR , located next to a complex of dense molecular gas , was confirmed .
The Ne and Mg abundances suggest a massive progenitor with a mass of > 20 M _ { \sun } .
Two extended regions emitting hard X-rays were identified ( corresponding to the known sources [ KLS2002 ] HX3 west and CXO J192318.5+140305 discovered with ASCA and Chandra , respectively ) , each of which has an additional point source inside and shows a power-law spectrum with \Gamma \approx 1.8 .
Based on their X-ray emission , both sources can be classified as PWN candidates .

Conclusions :