LONDON (Bloomberg) — Prime Minister Gordon Brown wrote to India's Prime Minister Manmohan Singh in December on concerns that it may be applying a tax law retrospectively on Vodafone Group Plc's acquisition of Hutchison Essar Ltd. shares, Brown's office confirmed in an e-mailed statement.

Indian income tax authorities are seeking $2 billion in capital gains tax from Vodafone over its purchase of Hutchison Essar three years ago, Bloomberg-UTV earlier reported.

Brown told Singh in the letter that taxing cross-border deals such as the Vodafone one could create uncertainty for foreign investors and affect the country's investment climate, Bloomberg-UTV reported.

India has replied to the letter saying the matter is in court and no decision has been taken, Bloomberg-UTV said.