Context : The discovery of true solar analogues is fundamental for a better understanding of the Sun and of the solar system .
Despite a number of efforts , this search has brought only to limited results among field stars .
The open cluster M67 offers a unique opportunity to search for solar analogues because its chemical composition and age are very similar to those of the Sun .

Aims : We analyze FLAMES spectra of a large number of M67 main sequence stars to identify solar analogues in this cluster .

Methods : We first determine cluster members which are likely not binaries , by combining proper motions and radial velocity measurements .
We concentrate our analysis on the determination of stellar effective temperature , using analyses of line-depth ratios and H \alpha wings , making a direct comparison with the solar spectrum obtained with the same instrument .
We also compute the lithium abundance for all the stars .

Results : Ten stars have both the temperature derived by line-depth ratios and H \alpha wings within 100 K from the Sun .
From these stars we derive , assuming a cluster reddening E ( B - V ) = 0.041 , the solar colour ( B - V ) _ { \odot } = 0.649 \pm 0.016 and a cluster distance modulus of 9.63 .
Five stars are most similar ( within 60 K ) to the Sun and candidates to be true solar twins .
These stars have also a low Li content , comparable to the photospheric abundance of the Sun , likely indicating a similar mixing evolution .

Conclusions : We find several candidates for the best solar analogues ever .
These stars are amenable to further spectroscopic investigations and planet search .
The solar colours are determined with rather high accuracy with an independent method , as well as the cluster distance modulus .