Context : After the detection of a 321-day periodicity in X-rays , HESS~J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries .
These sources are known to show extended radio structure on scales of milliarcseconds ( mas ) .

Aims : We present the expected extended radio emission on mas scales from HESS~J0632+057 .

Methods : We observed HESS~J0632+057 with the European VLBI Network ( EVN ) at 1.6 GHz in two epochs : during the January/February 2011 X-ray outburst and 30 days later .

Results : The VLBI image obtained during the outburst shows a compact \sim 0.4 mJy radio source , whereas 30 days later the source has faded and appears extended , with a projected size of \sim 75 AU .
The peak of the emission is displaced between runs 21 \pm 5 AU , which is bigger than the orbit size .
The position of the radio source is compatible with the Be star MWC~148 , which sets the proper motion of the binary system below 3 mas yr ^ { -1 } in each coordinate .
The brightness temperature of the source is above 2 \times 10 ^ { 6 } K. We compare the multiwavelength properties of HESS~J0632+057 with those of the previously known gamma-ray binaries .

Conclusions : HESS~J0632+057 displays extended and variable non-thermal radio emission .
Its morphology , size , and displacement on AU scales are similar to those found in the other gamma-ray binaries , PSR~B1259 $ - $ 63 , LS~5039 , and LS~I~+61~303 , supporting a similar nature for HESS~J0632+057 .