Context : The high sensitivity of the XMM-Newton instrumentation offers the opportunity to study faint and extended sources in the Milky Way and nearby galaxies such as the Large Magellanic Cloud ( LMC ) in detail .
The ROSAT Â PSPC survey of the LMC has revealed more than 700 X-ray sources , among which there are 46 supernova remnants ( SNRs ) and candidates .

Aims : We have observed the field around one of the most promising SNR candidates in the ROSAT Â PSPC catalogue , labelled [ HP99 ] Â 456 with XMM-Newton , to determine its nature .

Methods : We investigated the XMM-Newton data along with new radio-continuum , near infrared and optical data .
In particular , spectral and morphological studies of the X-ray and radio data were performed .

Results : The X-ray images obtained in different energy bands reveal two different structures .
Below 1.0 keV the X-ray emission shows the shell-like morphology of an SNR with a diameter of \sim  73 pc , one of the largest known in the LMC .
For its thermal spectrum we estimate an electron temperature of ( 0.49 \pm  0.12 )  keV assuming non-equilibrium ionisation .
The X-ray images above 1.0 keV reveal a less extended source within the SNR emission , located  1′ west of the centre of the SNR and coincident with bright point sources detected in radio-continuum .
This hard component has an extent of 0.9′ ( i.e . \sim  13 pc at a distance of \sim  50 kpc ) and a non-thermal spectrum .
The hard source coincides in position with the ROSAT Â source [ HP99 ] Â 456 and shows an indication for substructure .

Conclusions : We firmly identify a new SNR in the LMC with a shell-like morphology and a thermal spectrum .
Assuming the SNR to be in the Sedov phase yields an age of \sim  23 kyr .
We explore possible associations of the hard non-thermal emitting component with a pulsar wind nebula ( PWN ) or background active galactic nuclei ( AGN ) .