(Updates to close) Dec 18 (Reuters) - Australian shares...

(Updates to close)

Dec 18 (Reuters) - Australian shares finished higher on Monday, with broad-based gains driven by stronger commodity prices, financials stocks and optimism around U.S. tax reform.

Top U.S. Republicans said on Sunday they expected Congress to pass a tax code overhaul this week, with a Senate vote as early as Tuesday and President Donald Trump aiming to sign the bill by week's end.

The S&P/ASX 200 index (xjo) rose 0.7 percent or 41.9 points to 6,038.9 at the close of trade, ending a two-day losing streak. The benchmark declined 0.2 percent on Friday.

Financials led the upward march of the index, with Australia and New Zealand Banking Group Ltd (ANZ) accounting for most of the gains, rising 2.1 percent after it said it would start buying back up to A$1.5 billion ($1.15 billion) of its shares on-market.

Chinese steel futures rebounded from a one-week low on Friday boosting materials, with the Australian metals and mining index .AXMM climbing 1.5 percent to its highest since Nov. 27, recording six consecutive days of gains. [MET/L]

Global miner BHP (BHP) rose 2 percent to a 5-week high, while its rival Rio Tinto Ltd (RIO) ticked up 1.2 percent.

Cloud collaboration software provider Aconex Ltd (ACX) was the top performer as its shares skyrocketed 44.2 percent after it received a A$1.56 billion ($1.19 billion), buyout offer from U.S. software major Oracle Corp .

Advancing issues on the benchmark outnumbered declining ones 1.37-to-1.

New Zealand's benchmark S&P/NZX 50 index (nz50) fell 0.2 percent or 16.71 points to finish the session at 8,344.150.

Consumer confidence in New Zealand fell for the third month in a row in December as consumers braced for an economic slowdown, a survey showed on Monday.

Contact Energy Ltd (CEN) and Spark New Zealand Ltd (SPK) were the biggest drags on the index, down 3.6 percent and 1.1 percent, respectively.

($1 = 1.3057 Australian dollars)