* TSX ends down 0.8% at 33,318.39,

* Bank of Canada holds benchmark rate at 2.25%

* Materials group loses 2.3% as gold falls

* Oil settles nearly 7% higher boosting energy

(Updates at market close)

By Fergal Smith

April 29 (Reuters) - Canada's main stock index fell on

Wednesday to a three-week low, as rising uncertainty about the

duration of the Middle East conflict unnerved investors, with

railroad and metal mining shares among the biggest decliners.

The Toronto Stock Exchange's S&P/TSX composite index

ended down 265.95 points, or 0.8%, at 33,318.39,

marking its lowest closing level since April 7. It was the fifth

straight daily decline for the index, the longest losing streak

since December 2024.

"Middle East tensions are resurfacing ... so we have more

of a risk-off environment," said Michael Dehal, a senior

portfolio manager at Dehal Investment Partners at Raymond James.

U.S. President Donald Trump discussed how to mitigate the

impact of a possible months-long U.S. blockade of Iran's ports

with oil companies, a White House official said.

"As this war drags on, the inflation expectations continue

to rise up and that's going to cause markets to price in

interest rate hikes from central banks," Dehal said.

The Bank of Canada left its benchmark interest rate on hold

at 2.25% but said if oil prices stayed high and began pushing up

inflation, it might have to respond with consecutive rate hikes.

At least two rate increases this year have been priced into

the market by investors.

The materials sector, which includes Canadian

metal miners, was down 2.3%. The price of gold fell 1.1%

to hit a near one-month low as the U.S. Federal Reserve kept

rates unchanged as expected.

Industrials lost 1.6%, with shares of Canadian National

Railway Co ( CNI ) down 6% after the company's earnings missed

estimates.

CGI Inc ( GIB ) met earnings expectations. Still, shares

of the information technology consulting services company ended

10.8% lower.

Energy added 2.7% as the price of oil

settled nearly 7% higher at $106.88 a barrel.