PARIS, March 11 (Reuters) - The economic outlook in major industrialised economies is improving with the United States and Japan leading the way and activity in the euro zone also picking up, the OECD said on Monday.

The Organisation for Economic Cooperation and Development said its latest monthly leading indicator for the OECD as a whole pointed to firming growth.

Its composite leading indicator covering 33 OECD countries rose to 100.4 from 100.3 in December, rising further above the long-term average of 100.

The United States showed the strongest improvement with a reading of 100.9 for the world's largest economy, unchanged from December. The index for Japan rose meanwhile to 100.6 from 100.4.

The recession-hit euro zone also showed signs of improvement with its reading edging up to 99.7 from 99.6, led by regional powerhouse Germany. The OECD said the readings for Italy and France signalled "no further declines in growth".

The economic outlook in major industrialised economies is improving with the United States and Japan leading the way and activity in the euro zone also picking up, the OECD said on Monday.

The Organisation for Economic Cooperation and Development said its latest monthly leading indicator for the OECD as a whole pointed to firming growth.

Its composite leading indicator covering 33 OECD countries rose to 100.4 from 100.3 in December, rising further above the long-term average of 100.

The United States showed the strongest improvement with a reading of 100.9 for the world's largest economy, unchanged from December. The index for Japan rose meanwhile to 100.6 from 100.4.

The recession-hit euro zone also showed signs of improvement with its reading edging up to 99.7 from 99.6, led by regional powerhouse Germany. The OECD said the readings for Italy and France signalled "no further declines in growth".