Oct 20 (Reuters) - Roche raised its 2021 sales forecast on Wednesday after the Swiss drugmaker posted an 8% rise in nine-month revenues, powered by demand for COVID-19 tests and strength in the overall business helped by newly launched diagnostics platforms.

Overall sales in the nine months to September rose to 46.68 billion Swiss francs ($50.54 billion) from 43.98 billion Swiss francs last year, the Basel-based company said.

($1 = 0.9237 Swiss francs) (Reporting by Pushkala Aripaka in Bengaluru, editing by John Revill)