Online sales in the United States increased 12% in the first quarter of 2011, reported comScore. It is the fastest growth since before the 2008 financial crisis.

The research firm reported that online retail spending reached $38 billion in the first quarter, with the 25 most popular online retailers making up 67.7 percent of those sales.

Besides, comScore also added that the growth was driven by an increasing number of customers shopping online and more visits to online stores. However, the average size of online transactions fell 4 percent.

The last time online sales grew 12 percent or more was in the second quarter of 2008.