1. Introduction

2. X-ray cluster candidates
2.1. Selection of XMM-Newton observations
2.2. Selection of X-ray extended sources

3. Known clusters among the candidates

4. X-ray parameters of the known cluster sample with redshift measurements

5. Sample of cluster candidates

6. Discovery of two merging galaxy cluster candidates
6.1. Twin galaxy clusters 3XMM J010606.7+004925 and 3XMM J010610.0+005108 at z~0.26
6.2. Abell 0412 (z ~ 0.11)

7. Summary and outlook