Apple developers are being targeted from a  company that claims it owns the rights to Apple's own payment tools, demanding that they license from them or face steep legal action.

The move has developers worried as they face pressure to defend themselves with uncertainty whether Apple will step in to help offset the bill.

Developers Matt Braun, of Toldeo, Ohio, Patrick McCarron of Chicago, Ill., and James Thomson of Glasgow, Scotland have reported receiving legal threats.

Thomson who wrote the apps PCalc and DragThing, was served by hand this Friday.

They seem to be effectively claiming the rights to in-app purchase, but going after me, not Apple, said Thomson to Twitter.

The claims come from a Texas-based company called Lodsys, which said it has four patents relating to in-app purchases, interactive online ads, online help and subscription renewals.

The company  is a patent licensing company for inventions developed by Dan Abelow, a Harvard graduate who sold five of his patents outright in 2004: four went to Lodsys and one to a company called Webvention.

On its website, Lodsys claims ownership of patents related to technologies that provide for online purchasing of consumable supplies and sell upgrades or complimentary products, among others.

Lodysys did not respond to a request for comment.

A number of the developers, including Thomson, have referred the claims to Apple's legal department, on the basis that they have built their apps using Apple's developer toolkit.

Apple's iOS Paid Apps agreement says that developers will be reponsible for claims that any of the licensed applications and/or the end-user's possession or use of those licensed applications infringes the copyright or other intellectual property rights of any third party.

It is likely that Apple would step in and fight the claim as it threatens to tear the very fabric of Apple's development ecosystem.