From Pakistan to Lebanon, Saudi Arabia is scaling back its famed chequebook diplomacy, a longstanding policy of splashing petro-dollars in exchange for influence, which observers say has yielded few tangible gains.

For decades, the wealthy kingdom funnelled billions in aid to its allies and to its enemies' enemies in a bid to bolster its position as an Arab powerhouse and leader of the Muslim world.

But as plummeting demand has sapped its oil revenues, the kingdom is rethinking old alliances that Saudi observers say have swallowed their cash while offering little in return, at a time when its quest for regional supremacy is increasingly challenged by rivals Iran, Turkey and Qatar.

A swathe of regional countries, from Jordan and Lebanon to Egypt, Palestine and Pakistan, have been the top recipients of Saudi aid over the past decade, said Middle East expert Yasmine Farouk.

"The dual economic impact of the coronavirus and low oil prices, however, may lead Saudi Arabia to restructure and rationalise its aid," said Farouk, from the Carnegie Endowment for International Peace.

"The country is already seeking to end the perception of being 'an ATM'."

The kingdom has contributed billions to Lebanon's post-civil war reconstruction, but it has voiced frustration over its failure to rein in Hezbollah, a powerful group backed by its arch-enemy Iran.

"Saudi Arabia will not continue to pay Hezbollah's bills, and the Lebanese have to shoulder their responsibilities towards their country," Saudi columnist Khalid al-Sulaiman wrote recently for the pro-government Okaz newspaper.

"It is no longer possible for Saudi Arabia to continue paying billions to Lebanon in the morning and receive insults at night.

"This situation is no longer compatible with the new Saudi foreign policy, as Saudi money does not fall from the sky or grow in the desert."

- 'Party is over' -

Saudi Arabia also appears frustrated with Pakistan after the longstanding ally pushed Riyadh to take a firm stand on the disputed region of Kashmir and threatened to take the issue to other Muslim forums.

Such a threat is particularly disconcerting for Saudi Arabia, which is home to Islam's holiest sites and views itself as the leader of the Muslim world.

The kingdom recently recalled $1 billion of a $3 billion loan from cash-strapped Pakistan, and an expired multi-billion dollar oil credit facility to Islamabad has not been renewed, a diplomatic source told AFP.

"Pakistani elites have a bad habit of taking Saudi support for granted, given what Saudi has done for Pakistan over the decades," tweeted Ali Shihabi, a Saudi author and analyst.

"Well the party is over, and Pakistan needs to deliver value to this relationship. It's no longer a free lunch or a one-way street."

Riyadh's ties with Pakistan have historically been "very warm" but the relationship has been lopsided, said Saudi prince Talal bin Mohammad al-Faisal.

"It (has) only benefited one side in 'real world' terms," he tweeted.

"That side is Pakistan."

- 'Take their money' -

Pakistan and Egypt, another ally which has received billions in aid, rebuffed calls for ground troops to support the Saudi-led military campaign in Yemen against Iran-linked Huthi rebels.

Further stirring consternation in Riyadh, a leaked 2015 audio recording showed Egypt's President Abdel Fattah al-Sisi allegedly mocking Gulf powers including Saudi Arabia, saying they were rolling in money "like rice".

That sentiment was echoed in 2018 by US President Donald Trump when he hosted Crown Prince Mohammed bin Salman in the Oval Office and held up a chart listing military hardware sales worth billions to Riyadh.

"Take their money," Trump told NBC News the following year, justifying backing the kingdom's rulers after journalist Jamal Khashoggi's murder sparked global uproar.

With so many of its relationships rendered transactional, Riyadh is struggling to win respect and its once-leading role in the Muslim world is increasingly challenged by its rivals, observers say.

The Saudis are increasingly resentful of "ungrateful" allies, said Farouk.

States that have traditionally benefited from Saudi largesse, including Jordan, Lebanon and Palestine, have "already seen instances in which aid was frozen, decreased or cut off", she added.