(Adds details throughout and updates prices to close)

* TSX ends up 213.89 points, or 1.1%, at 19,987.23

* Posts highest closing level since Aug. 25

* Energy climbs nearly 2%; oil settles up 1.1%

* Financials add 1.1%

TORONTO, Sept 12 (Reuters) - Canada's main stock index rose on Monday to its loftiest closing level in nearly three weeks, as energy stocks climbed on higher crude oil prices and were supported by gains for financial and consumer discretionary shares.

The Toronto Stock Exchange's S&P/TSX composite index ended up 213.89 points, or 1.1%, at 19,987.23. It was the fourth straight day the index has closed in positive territory and the highest closing level since Aug. 25.

Wall Street also advanced as investors awaited crucial U.S. inflation data on Tuesday for any signs that price pressures might be easing.

"This week is all about U.S. inflation reading and that is going to set the tone for the next interest rate decision out of the U.S. and then the Canadian markets will move based on U.S. economic data," said Allan Small, senior investment adviser of the Allan Small Financial Group with iA Private Wealth.

The Toronto market has been hovering between a record high it notched in March and July's 16-month low.

The energy sector climbed nearly 2%, tracking rising oil prices as supply concerns mount heading into the winter. U.S. crude oil futures settled 1.1% higher at $87.78 a barrel.

Shares of Tamarack Valley Energy Ltd clawed back earlier declines to end up 0.25%. The company said it will buy oil producer Deltastream Energy Corp in a deal valued at C$1.425 billion ($1.10 billion), making it the largest producer in Alberta's Clearwater.

Heavily weighted financials added 1.1% and consumer discretionary was up 1.4%.

Domestic data showed household indebtedness climbing to a record high. (Reporting by Fergal Smith; Additional reporting by Aniruddha Ghosh and Johann Cherian in Bengaluru; Editing by Krishna Chandra Eluri and Lisa Shumaker)