evidence: On 13 November, Malaysia's Agent, Ambassador-at-Large Abdul Kadir Mohamad, alleged that Singapore was trying to "subvert" a 150-year-old arrangement under which Singapore operated Horsburgh Lighthouse on Pedra Branca, which was Malaysia's territory. He also suggested that if permitted to do so, Singapore would upset the peace and stability of the area where the island is located. He said that if Singapore reclaimed land around Pedra Branca, "[q]uite apart from the possible effects on the environment and navigation in the Strait, this could lead to potentially serious changes to the security arrangements in the eastern entrance of the Strait".[66] According to Malaysian Attorney-General Abdul Gani Patail, Singapore had first raised the issue of sovereignty over Pedra Branca on 13 April 1978 during a meeting between officials, saying it had "incontrovertible legal evidence" of its sovereignty over the island though it had never produced any documents in support. Prior to that, the sovereignty of the island had never been disputed. The 1980 statement by the then Malaysian Prime Minister Tun Hussein Onn concerning the "unclear" position of the island had also been premised on these documents which former Singapore Prime Minister Lee Kuan Yew had claimed were in Singapore's possession.