* FTSE 100, FTSE 250 both down 0.1%

Aug 3 (Reuters) - London's FTSE 100 edged lower on Monday as upbeat China factory activity data was offset by a slide in shares of HSBC after the bank posted a 65% plunge in first-half profit and warned of soaring potential loan losses due to the COVID-19 crisis.

HSBC, Europe's biggest bank by assets, fell 4.4% to the bottom of the FTSE 100 as the health crisis hammered the lender's retail and corporate customers worldwide.

The stock was also the biggest drag on the blue-chip FTSE 100, but material, energy and industrial sectors limited the decline. At 0711 GMT, the index was down 0.1%.

The mid-cap FTSE 250 also slipped 0.1%, dragged by real estate, consumer discretionary and financial stocks.

Engineering firm Senior Plc tumbled 11% after swinging to a first-half loss and shelving its interim dividend.

(Reporting by Sagarika Jaisinghani in Bengaluru, Editing by Sherry Jacob-Phillips)