Diplomatic tensions between Singapore and Malaysia are rising as the two often-fractious neighbours trade barbs about ownership of an island that both claim, and a host of other disputes. Diplomats in the city-state say they suspect that Kuala Lumpur may be increasing the pressure in the wake of a recent decision in its favour by the International Court of Justice (ICJ) over a separate island dispute with Indonesia. Observers add that they detect a growing sense of irritation among Singaporean leaders as they try to iron out a series of niggling issues with Malaysia that have soured relations since the two states' separation in 1965. One diplomat said yesterday that the level of rancour had reached heights not seen in 20 years after a series of hard-hitting exchanges from the two sides, including an emergency debate in Singapore's parliament on Saturday. The blunt exchanges have included the release by Singapore Foreign Minister Shanmugam Jayakumar of correspondence between the two countries' leaders over a protracted dispute about water supply, another thorny bilateral issue. Malaysian Foreign Minister Syed Hamid Albar expressed unhappiness that Singapore has made public 19 letters and diplomatic exchanges between the two countries, mainly concerning Malaysian water for the city state. 'The matter is still being negotiated . . . it is a sign they lack good faith,' Mr Syed Hamid said. Diplomats and political analysts said they believe their publication took Malaysian officials by surprise. Singapore decided to show all because it was unhappy with the way the Malaysian media had 'misled' the public over several issues. The documents cover exchanges between Prime Minister Mahathir Mohamad and Singapore leaders Lee Kuan Yew and Goh Chok Tong over a three-year period from May 1999. They are couched in polite language and reveal deep differences on a price for water. Singapore, which is paying three Malaysian sen per 4,540 litres, accuses Malaysia of wanting vastly more - 8.45 ringgit (HK$17.40) for the same quantity. Malaysia says it only wants a fair price. The issue at the heart of the latest flare-up is a dispute over Pedra Branca, which Malaysia refers to as Batu Putih. An early-January collision between a Singapore naval vessel and a container ship in the waters around the islet refocused attention on the scrap of rock at the eastern entrance to the Strait of Singapore. The city's officials say that Kuala Lumpur staked a claim to the islet only in 1979, including it on a map of its territorial waters. They say Singapore has controlled Pedra Branca since the 1840s. The temperature of the rhetoric has grown even as both sides are preparing to send the issue to the ICJ for a resolution. Singapore and Kuala Lumpur are set to sign a deal to refer the case to the Hague-based body on February 6. Malaysia has done well out of the ICJ in recent months. Last month, the court ruled that Sipidan and Ligitan off the eastern coast of Malaysia's Sabah state belonged to Kuala Lumpur, rebuffing a long-standing claim by Indonesia. Reaffirming the importance that the state attaches to the case, Mr Jayakumar said Singapore's naval patrols would continue off Pedra Branca. Dr Mahathir responded by promising to do the same. The spats have included the supply of water from Malaysia's southern province of Johor to Singapore, and infrastructure projects. Singapore officials privately say that Malaysia often patronises it as a type of 'younger brother'. In reply, Malaysians have accused Singapore of 'arrogant behaviour'.