Waitrose has reported a 3.4% increase in annual like-for-like sales, as the supermarket’s parent company The John Lewis Partnership handed staff a larger than expected bonus of 17% of salary.

The supermarket said there was a “noticeable acceleration” in the sales growth in the second half of the year ending 26 January as its investment in lower prices kicked in. In September, Waitrose reported a 2.2% increase in like-for-like sales for the first half of the year.

The company added that investment in new products had delivered results. It said it had brought out 4,700 new and improved products in 2012 – 1,000 more than in 2011.

Operating profits at Waitrose also grew by 12.2% to £292.3m.

Waitrose sister company John Lewis also performed well and the John Lewis Partnership as a whole reported a 15% increase in operating profits to £452.4m.

The good results allowed the partnership to hand staff a bonus of 17%, equal to nearly nine weeks’ pay, which was above analyst predictions of 15% or 16% this week.

“We were encouraged by the acceleration in the rate of sales growth during the year, particularly in the final quarter. Although the market remains challenging, the Partnership has adapted quickly and successfully and we saw the benefits this year,” said John Lewis Partnership chairman Charlie Mayfield.