The key Christmas sales day for online retailers, Mega Monday, is expected to happen a week later this year.

The IMRG said online year-on-year sales jumped 14 per cent to£320 million on Monday (December 8) – traditionally the biggest day of the year online. However, e-tailers claim the best is yet to come.

Google industry head for retail Paul Frantz said: “The Christmas peak is happening one and a half to two weeks later this year. With retailers offering more aggressive delivery dates, next Monday could in fact be the biggest day online.”

M and M Direct chief executive Steve Robinson said that it had a record day on Monday, with sales exceeding£1 million. He said online retailers “still had surprises to come” this year.

Sunday is shaping up to be an equally big day for e-tail. Asos chief executive Nick Robertson said that last Sunday had been its best day and that the coming weekend looked like it would be very strong too.

E-tailers maintain a later spike in online trade has been influenced by several factors including an increase in trust that e-tailers can deliver online. Many online players, including Shop Direct Group, Amazon and Asos, are offering express delivery as late as December 24.