Updates at market close

By Tharuniyaa Lakshmi and Fergal Smith

TORONTO, June 10 (Reuters) - Canada's main stock index fell to a three-week low on Wednesday as U.S.-Iran tensions rose, while the Bank of Canada left interest rates on hold as expected and Apotex Health clinched the largest initial public offering for the market in five years.

The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE ended down 260.37 points, or 0.8%, at 34,151.32, marking its lowest closing level since May 19.

• Major U.S. stock indexes posted steeper declines as chipmaker shares extended recent losses and tensions rose between the U.S. and Iran.

• U.S. President Donald Trump said the U.S. would attack Iran again "very hard" following one of the most significant exchanges of fire overnight since an April ceasefire. He accused Tehran of taking too long to negotiate a deal.

• "This sort of sabre-rattling in Iran is not helping," said Brian Madden, chief investment officer at First Avenue Investment Counsel.

• The materials group .GSPTTMT, which includes metal mining stocks, fell 4%. The price of gold was down 4.4% as investors worried that the war could lead to higher interest rates globally to curb inflation.

• The BoC left the door open to interest rate hikes if increased inflation due to higher energy prices grows more widespread but also interest rate cuts if the U.S. imposes new tariffs on Canadian goods.

• "By keeping both cuts and hikes in play the bank is acknowledging that policymakers are operating with genuine uncertainty," said Michael Constantino, CEO of Webull Canada.

• Energy .SPTTEN helped limit the TSX's decline, rising 1.6%. The price of oil CLc1 settled 2.1% higher at $90.03 a barrel.

• Shares of Canadian generic drug manufacturer Apotex APTX.TO ended 12.5% above their IPO price of C$24. The IPO generated about C$1.3 billion in gross proceeds, making it the largest for the TSX since 2021.