Sainsbury's Christmas sales just beat forecastsGÇï

LONDON, Jan 10 (Reuters) - Sainsbury's, Britain's No. 2 supermarket group, reported a slight beat to forecasts for sales growth in its key Christmas quarter and said it was edging up its full-year profit guidance, helped by synergies from the Argos business.

The firm, which bought electricals and toys retailer Argos in 2016, said on Wednesday total retail like-for-like sales, excluding fuel, rose percent 1.1 in the 15 weeks to Jan. 6, its fiscal third quarter.

That compared to analysts' average forecast of 0.9 percent and growth of 0.6 percent in the previous quarter.

It said underlying profit before tax for the full 2017-18 year was now expected to be moderately ahead of the published analysts' consensus - an underlying pretax profit of 559 million pounds ($755.77 million), down from 581 million in 2016-17. ($1 = 0.7396 pounds) (Reporting by James Davey; editing by Kate Holton)