The Land Transport Authority (LTA) will call a tender in the first quarter of next year for a consultant to conduct an environmental impact assessment (EIA) for the future Cross Island Line.

This assessment will focus on the portion of the MRT line around the Central Catchment Nature Reserve, and determine how various alignments could affect the reserve.

When completed in 2016, the EIA report will help the government assess the impact of the Cross Island Line's alignment on the nature reserve. Nature and environment groups had earlier expressed concern that works for the MRT line could cause irreparable damage to the reserve, and called for an alignment that skirted around it.

At a briefing on Wednesday, LTA chief executive Chew Hock Yong said the nature groups will assist the authorities in scoping the EIA. Announced in January this year, the 50km Cross Island Line will serve as an alternative to the current East-West Line. It is expected to be ready in 2030.