A study by a group hoping to counter some anti-illegal immigrant sentiment at the legislature estimates that undocumented immigrants contribute around $400 million to Virginia's economy annually in taxes.

The Commonwealth Institute for Fiscal Analysis on Thursday unveiled its study estimating that illegal immigrants contribute between $379 million and $453 million a year in income, sales, property and other taxes.

Institute executive director Michael Cassidy says too often the debate centers on the costs of providing services to illegal aliens instead of their contributions.

Legislators who want to crack down on illegal immigration dismissed the study, saying undocumented immigrants are in America and Virginia to benefit from, not improve, the economy.