Japanese convenience store retailer Lawson Inc has reported higher operating profit and sales for the first nine months of its financial year, although charges hit its bottom line.

Lawson's operating profit increased by more than 8% for the nine months to the end of November on the back of a 9% rise in sales.

The retailer, which operates over 10,000 stores in Japan, on Tuesday (10 January) posted an 8.4% increase in operating profit to JPY49.77bn (US$648.9m). Sales were up 9% at JPY360.87trn.

Net profit was down 0.8% at JPY20.6bn due to a charge of JPY8.29bn after an adjustment for accounting standard changes for asset retirement obligations. Lawson also recorded costs of JPY3.42bn that were linked to the earthquake and tsunami that rocked Japan last March. 

Lawson said the Japanese economy had picked up "gradually" since the disaster and that sales in the convenience sector had been "robust".

The company maintained its profit and sales estimates for its full financial year. Net profit is expected to fall by more than 7%, although operating profit is forecast to be up 10.7%. Lawson has predicted that its annual sales will be up 7.2%.