The region around SGR 1806-20 and its host stellar cluster Cl* 1806-20 is a potentially important site of particle acceleration .
The soft \gamma - ray repeater and Cl* 1806-20 , which also contains several very massive stars including a luminous blue variable hypergiant LBV 1806-20 , are capable of depositing a large amount of energy to the surroundings .
Using the data taken with the Fermi Large Area Telescope ( LAT ) , we identified an extended LAT source to the south-west of Cl* 1806-20 .
The centroid of the 1-50 GeV emission is consistent with that of HESS J1808-204 ( until now unidentified ) .
The LAT spectrum is best-fit by a broken power-law with the break energy E _ { \mathrm { b } } = 297 \pm 15 MeV .
The index above E _ { \mathrm { b } } is 2.60 \pm 0.04 , and is consistent with the flux and spectral index above 100 GeV for HESS J1808-204 , suggesting an association between the two sources .
Meanwhile , the interacting supernova remnant SNR G9.7-0.0 is also a potential contributor to the LAT flux .
A tentative flux enhancement at the MeV band during a 45-day interval ( 2011 Jan 21 - 2011 Mar 7 ) is also reported .
We discuss possible origins of the extended LAT source in the context of both leptonic and hadronic scenarios .