BENGALURU - Recent stimulus measures announced by the Indian government will be insufficient to boost economic growth significantly, said a majority of economists in a Reuters poll who predicted two more interest rate cuts this year, in October and December.

To revive the ailing economy, the government in September announced a steep cut in the corporate tax rate - to 22% from 30% - triggering the biggest intraday gain in Indian stocks in more than a decade.

That along with other measures, including a rollback of a higher surcharge on foreign portfolio investment - introduced in the budget in July - led international investors to become net buyers of Indian assets in September.

But nearly 60% of around 50 economists who answered an additional question said those stimulus measures were unlikely to have a notable impact on the economy.

"While the cut in corporate taxes is sharp, its actual impact on growth is uncertain. Given that the current problem is of weak demand, a demand augmenting measure would have been more productive," said Rini Sen, India economist at ANZ.

Although the economy is expected to have recovered last quarter from the sharp slowdown in the three months prior, economists downgraded their growth outlook for this fiscal year and next from three months ago.

The Sept. 24-30 poll of over 50 economists predicted gross domestic product growth to average 6.1% this fiscal year, the lowest since polling began for the period in April last year.

If realised, that would mark the slowest pace of growth in seven years.

The economy was then expected to expand 6.8% next fiscal year, a downgrade from 7.2% predicted in the July poll.

That weak outlook was driven by lack of clarity on when and how the U.S.-China trade war will end, which has already hurt business sentiment, manufacturing activity and the global economy.

But some economists argued recent measures announced by the Indian government, along with monetary policy easing, would likely boost Asia's third-largest economy.

The Reserve Bank of India has already eased policy by a cumulative 110 basis points this year.

It is now expected to cut its repo rate by 25 basis points on Friday, making it the fifth meeting in a row of easing, and is then predicted to follow that up by with another 15 basis points slice in December, taking the key rate to 5.0%.

But the RBI is then forecast to keep rates unchanged until 2021 at least.

"It looks like the authorities - both the government and the central bank - are firing up all cylinders to provide stimulus to the economy...with stimulus announced so far should start to revive growth going forward," said Prakash Sakpal, Asia economist at ING.

When asked how many more rate cuts it would take to boost growth significantly, nearly 45% of economists said cumulative rate cuts up to 50 basis points will be needed.

Eleven said between 50 and 100 basis points would do the trick, while two said over a percentage point.

The outlook for further policy easing was also backed by subdued inflation, which is not expected to breach the central bank's medium-term target of 4% until the fourth quarter of 2020.

"With inflation remaining under control, monetary stimulus in combination with the recent fiscal measures are likely to be growth supportive," said Shashank Mendiratta, economist at IBM.

But not everyone agreed with that view.

Nearly 30% of respondents said boosting economic growth significantly is beyond the RBI's immediate control.

"Not only monetary policy but also short-term measures that the government has taken so far, are used to sugar-coat the wrong policy trajectory from a structural point of view," said Hugo Erken, head of international economics at Rabobank.

"Because what India really needs is a large-scale reform package on several fronts."

A weak growth outlook, ongoing concerns about the U.S.-China trade war and the prospect of further RBI easing are all expected to hurt the Indian rupee INR= in coming months.

After rallying as much as 3% against the dollar in September, the rupee is forecast to reverse most of those gains to trade at 72.50 per dollar in a year, compared to 70.70 on Monday.

"Despite the fact that both monetary and fiscal levers are now being deployed to prop up growth, a material recovery is still elusive," added ANZ's Sen.

"We therefore see limited scope for the current (rupee) rally to last unless demand sharply recovers. In addition, global risks including worsening in trade uncertainties or an oil price surge could add to rupee volatility."

(Polling by Shaloo Shrivastava and Anisha Sheth Editing by Rahul Karunakar and Lisa Shumaker) ((Indradip.Ghosh@thomsonreuters.com;))