Competition in the seven-inch tablet market could be getting much hotter in the coming months, as NPD Group Inc. claims Amazon.com Inc. (Nasdaq: AMZN) is working on up to four new Kindle Fire tablets.

CNET reports that NPD DisplaySearch Senior Analyst Richard Shim is predicting that Amazon could launch up to four "Kindle Fire 2" tablets this year.

The analyst suggests that the retailer will have three new tablets with seven-inch displays: one without a camera, one with a camera, and one with both 4G Long Term Evolution (LTE) and a camera on board. These would arrive in August or September. The analyst also claims that Amazon could be working on an 8.9-inch display model for the fourth quarter.

The Eastern Morning Herald points to reports out of China that suggest Amazon has already ordered its first 2 million units of the Kindle Fire 2 from manufacturer Quanta Computer Inc. .

Rumors about an updated version of Amazon's popular Android tablet have been swirling for months. They have been given fresh focus by the launch of Google (Nasdaq: GOOG)'s first tablet -- the Nexus 7 -- last week and revitalized chatter about an upcoming iPad Mini from Apple Inc. (Nasdaq: AAPL)

Despite all the renewed interest in the smaller seven-inch tablet form factor, however, the larger iPad is still the best-selling tablet yet launched.

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— Dan Jones, Site Editor, Light Reading Mobile