That's according to Pocket Gamer, which cites data from recent weekly Gfk Chart-Track reports, which it says were obtained from a source.
The site reports that 3DS will reach one million sales early next month, taking roughly three months longer than its predecessor did to hit the milestone. DS reached one million UK sales in just 51 weeks.
Gfk Chart-Track's business group director Dorian Bloch noted that the difference in price of the systems was an important factor - Nintendo's older handheld was sold at an average price of just £98 in its first ten weeks, versus £202 for 3DS, although the newer system now retails for around £140 following a price cut last August.
PocketGamer also reports that the original PSP had sold 350,000 units after ten weeks on sale, 3.5 times as many as Vita achieved during the same period.
Chart-Track's Bloch noted that the average Vita cost £232 in the system's first ten weeks on sale, versus £178 for the average PSP, adding: "[PS Vita] was launched at a traditionally quiet time, and [PSP] was launched in the build-up to Q4."
Sony CEO Kaz Hirai said earlier this month that worldwide Vita sales stood at 1.8 million at the end of the company's financial year on March 31, 2012.
He called it a "good start", but acknowledged that "software and services must be strengthened" if the company's to hit its targets, which include ten million Vita sales during the current business year.