Malaysian Prime Minister Mahathir Mohamad said Monday he wants to renegotiate a "ridiculous" water supply agreement with Singapore, the latest sign of fraying ties between the neighbours since last month's shock election.
The 92-year-old returned for a second time as premier after his opposition alliance scored an unexpected victory at the polls, toppling a long-ruling coalition which Mahathir himself had once headed.
During his first spell in charge of the country from 1981-2003, Malaysia had famously prickly ties with Singapore -- and Mahathir has wasted no time in taking aim at the tiny city-state again.
In his latest salvo, he said it was "manifestly ridiculous" that Kuala Lumpur sells water for three Malaysian cents (less than one US cent) per thousand gallons to its resource-poor neighbour, under a decades-old agreement.
"That was okay way back in the 1990s or 1930s. But now what can you buy with three sen (cents)? Nothing," he told Singapore broadcaster Channel NewsAsia in an interview.
Asked about plans to renegotiate the water supply agreement, he said: "We are studying the case properly and we'll make a presentation."
Much of Singapore's water comes from Malaysia's southern state of Johor. Under a 1962 agreement, Singapore can draw up to 250 million gallons of water per day from the Johor River.
Singapore's foreign ministry said in a statement the water deal was "guaranteed by both governments" as part of an agreement which underpinned their division into separate states in 1965.
"Both sides must comply fully with all the provisions of these agreements," it said.
The neighbours were part of the same country for two years from 1963 but it was a stormy union, and Singapore was expelled from the Malaysian Federation as tensions mounted over ethnic issues.
Relations in subsequent decades were punctuated by occasional bickering, on many occasions over the water supply issue. But they were largely warm under the previous Malaysian government, led by scandal-mired Najib Razak.
However ties already look rocky since Mahathir's return to office.
In just a few weeks, he has put a planned high-speed railway linking Kuala Lumpur to Singapore on hold, and announced that Malaysia wants to develop an island on rocks at the entrance to the Singapore Strait, an area of great strategic importance to the city-state.