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Video game sales slumped in the US - their biggest market - in January.

NPD group said stores sold $1.14bn (£720m) worth of games over the month, down 34% on the previous year. It added that hardware sales were down 38%.

The consumer data provider linked the drop to a lack of major new releases.

Other analysts also pointed to worries about the economy and said this might have an impact on the upcoming launch of Sony's PlayStation Vita console.

NPD said that Activision Blizzard's Call of Duty: Modern Warfare 3 was the month's best-selling title. It was followed by Just Dance 3, Elder Scrolls V: Skyrim and NBA 2K12.

Microsoft's Xbox 360 held onto its title as the top selling hardware platform for the sixth month running.

"While the lack of new launches was a major reason for software declines, games which launched in the last three months of 2011 also performed poorly in January 2012, down 31% in units compared to fourth quarter launches in January 2011," NPD analyst Liam Callahan added.

"As shoppers were not drawn to stores due to new launch activity, this potentially impacted additional software purchases made on impulse."

The video games news website, IGN, said it had noted a similar drop-off in activity in the UK market. It said sales should pick up when Mass Effect 3 goes on sale in March, but noted that shoppers were worried.

"You can't really deny that the economy is a factor," Keza MacDonald, the firm's UK games editor, told the ´óÏó´«Ã½.

"The lack of big new releases is just a tiny bit of the picture. The fact people are buying less games shows up in the US, European and Japanese data.

"People are just buying fewer games because they have less money to spend. The data before Christmas was also not particularly strong."

The news comes as Sony prepares the global launch of its new PlayStation Vita games console. The device goes on sale across Europe, Australia and the Americas on 22 February.

Analysts at IHS Screen Digest have forecast 7 million units will be sold by the end of the year. They say that would be 25% less than what its predecessor the PlayStation Portable System achieved over its initial roll-out.

"I think there is a segment of the population - potentially a narrowing segment - which is still engaged by specialist devices such as handheld consoles," said the firm's head of games, Piers Harding-Rolls.

"But it is a very price-driven situation and part of that equation is definitely the content on offer.

"Sony has hit the mark with a strong line-up at launch which should drive strong initial sales, but there's the potential that demand will drop off quite significantly after the first few weeks."

Industry watchers note that the console will have to compete for attention with Apple's latest iPad which thesuggests will launch in March.

"A lot of the market for handheld gaming was kids and that market has completely shifted to iPhones, Android phones and touchscreen tablets," said Ms MacDonald.

"The Vita is a nice bit of kit - it has gadget appeal - but I'm not sure it has mainstream appeal."