* Says told by environment ministry to file new EIA

* Says new EIA to severely hit project schedule

* Says will require project to be redesigned

* Shares plunge 47 pct

April 26 (Reuters) - Greystar Resources GSL.TO said the Colombian government has told it to file new environmental impact assessment (EIA) for its gold-and-silver mine at Angostura, which will severely hit the project schedule and may have a material effect on its economic viability.

Shares of the company nearly halved in value to C$3.45 Monday morning on the Toronto Stock Exchange.

The ministry of environment, housing and territorial development has requested that the new Angostura EIA adjust the occupied area to an elevation below 3,200 meters, the company said in a statement.

The request requires that mining and exploration activity must be excluded from the Paramo ecosystem, which mostly consists of glacier-formed valleys and plains with lakes.

Greystar, which restarted its operations in Colombia in 2003 after a halt in 1999 following the kidnapping of a contractor, said the request would require the Angostura project to be completely redesigned.

The company said it had started to secure $650 million in project finance from international sources, and was completing a definitive feasibility study on the Angostura project.

Greystar had also begun the process of filing an appeal of the notification, it said. (Reporting by Bhaswati Mukhopadhyay in Bangalore; Editing by Unnikrishnan Nair)