BUFFALO, N.Y. (AP) — General Motors Co. has chosen its Tonawanda Engine plant to build a new V8 engine, a person familiar with the discussions said Monday.

The auto maker has scheduled a news conference at the suburban Buffalo plant for Tuesday. GM will announce a $400 million investment for a next-generation engine that the person said will create or retain more than 700 jobs. The person spoke on the condition of anonymity because he was not authorized to disclose the information ahead of the announcement.

A GM news release said Tuesday's press conference would involve "positive manufacturing news." Spokeswoman Mary Ann Brown would not elaborate.

It is the second big investment in the Tonawanda plant to be announced this year. In February, General Motors announced the western New York facility would receive about $425 million in upgrades to begin building a new version of its four-cylinder Ecotec engine in 2012.

Since then, local authorities have been lobbying for even more work for the plant, which has seen its work force dwindle from 4,350 20 years ago to about 650. The Erie County Industrial Development Agency earlier this month approved a package of tax breaks for future work. Sen. Charles Schumer, meanwhile, wrote to GM Chairman Edward Whitacre promoting the Tonawanda site for both the new V8 line and a V6 engine.

"We are starting to see the plant make real progress towards long term growth and we have an opportunity to build on that momentum," the New York Democrat wrote.

General Motors also has an announcement planned in southern Indiana Tuesday which it said would involve hundreds of jobs at a plant there.