US President-elect Donald Trump has questioned the effectiveness of the United Nations, saying it was just a club for people to "have a good time", after the UN Security Council voted last week to condemn Israeli settlements in the West Bank and east Jerusalem.

Key points: President-elect Donald Trump took to Twitter to criticise the UN following Israeli settlement condemnation

President-elect Donald Trump took to Twitter to criticise the UN following Israeli settlement condemnation Mr Trump has shifted his stance in the past year, taking a pro-Israel tone

Mr Trump has shifted his stance in the past year, taking a pro-Israel tone He also declared his election has boosted the US economy

Mr Trump wrote on Twitter that the UN had "such great potential", but it had become "just a club for people to get together, talk and have a good time. So sad!"

On Friday after the vote, Mr Trump warned, "As to the UN, things will be different after January 20th", referring to the day he takes office.

The decision by the Obama administration to abstain from Friday's UN vote brushed aside Mr Trump's demands that the US exercise its veto, and provided a climax to years of icy relations with Israel's leadership.

On the Middle East, Mr Trump said last December that he wanted to be "very neutral" on Israel-Palestinian issues.

But his tone became decidedly more pro-Israel as the presidential campaign progressed. He has spoken disparagingly of Palestinians, saying they have been "taken over" by, or are condoning, militant groups.

This year the UN Security Council has approved over 70 legally binding resolutions, including new sanctions on North Korea and measures tackling conflicts and authorising the UN's far-flung peacekeeping operations around the world.

The General Assembly has also approved dozens of resolutions on issues, like the role of diamonds in fuelling conflicts; condemned human rights abuses in Iran and North Korea; and authorised an investigation of alleged war crimes in Syria.

Mr Trump's criticism of the UN is by no means unique — while the organisation does engage in large-scale humanitarian and peacekeeping efforts, its massive bureaucracy has long been a source of controversy.

The organisation has been accused by some Western governments of being inefficient and frivolous, while developing nations have said it is overly influenced by wealthier nations.

'The world was gloomy before I won'

That was only one subject on which Mr Trump tweeted Monday. In an evening post, he wrote that he believed his election as President had boosted the economy.

"The world was gloomy before I won — there was no hope," he said in a post on his Twitter account.

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"Now, the market is up nearly 10 per cent and Christmas spending is over a trillion dollars."

Markets are up since Mr Trump won the general election, but the Standard & Poor's 500 is up only about 6 per cent since election day, while the Dow has risen more than 8 per cent.

As for holiday spending, auditing and accounting firm Deloitte projected in September that total US 2016 holiday sales were expected to exceed $US1 trillion, representing a 3.6 per cent to 4.0 per cent increase in holiday sales from November through January.

AP