AT&T Inc said on Wednesday it would double its wireless data network speeds as part of an upgrade that it aims to kick off later this year and complete in 2011.

The second biggest U.S. mobile service said its plan, which includes the expansion of its existing wireless data network from 350 metropolitan areas to 370 this year, would be covered by its previously announced capital spending budget of $17 billion to $18 billion for 2009.

The increase to its mobile Web surfing speeds involves an upgrade of a network technology known as High Speed Packet Access (HSPA) that AT&T already uses. The upgrade is expected to increase AT&T's theoretical network speed to 7.2 megabits per second from current levels of 3 megabits per second, the company said.

However, actual network speeds can vary hugely once a network is loaded with customers. AT&T said it would have multiple laptop network cards and smartphones available to take advantage of the upgrade later this year.

The company also said it would start tests for its next network technology upgrade with a technology known as Long Term Evolution (LTE) in 2010 and plans to start building LTE into its network in 2011.

Its bigger rival Verizon Wireless, owned by Verizon Communications Inc and Vodafone Group Plc, plans to already start installing LTE into its network later in 2009, a year ahead of AT&T.

Clearwire Corp is building a rival high-speed network based on WiMax, another emerging technology.

(Reporting by Sinead Carew; Editing by Richard Chang)

Electronics Broadband AT&T