Former Penang Chief Minister Koh Tsu Koon today shot down a challenge from his successor Lim Guan Eng demanding proof of a purported RM4 billion investment plan by an American company in Penang.

NONE Koh ( left ), a Minister in the Prime Minister's Department, denied having ever made such an announcement.

"When did I ever promise a RM4 billion investment as he claimed? What is he talking about? Don't mislead the people of Penang," he said at a brief press conference in the Parliament lobby.

Koh is currently embroiled in a tit-for-tat exchange with Lim over the proposed Greater Penang Masterplan mooted by the DAP secretary-general's administration.

In a statement today, Lim attacked Koh for claiming he had played a key role in securing a RM4 billion investment to set up a Global Excellence Centre in Penang, without any news coverage or evidence to support his claim.

Koh, who is also Gerakan president, dismissed his rival's claims as irresponsible, stressing that personal attacks can only go so far.

"I seldom talk about him, but he talks about me once or twice a week. He can attack me, it's an obsession... but don't mislead the people."

Koh, who said he was fed up with Lim's allegations, issued a challenge of his own to his successor.

"He asked me to give evidence of the RM4 billion investment in Penang, so I challenge him to give evidence that I made such an announcement," he said, though he declined to comment when asked if he would sue Lim.

Lim, when met in the Parliament lobby after the press conference, laughed off Koh's challenge.

"Ooo... I'm shaking. Let him have his say today, I will respond tomorrow," he quipped, before leaving Parliament.