Penang Chief Minister Lim Guan Eng has expressed shock over the alleged "wild and baseless" challenge about the goods and services tax (GST) hurled at him by Sawarak Chief Minister Adenan Satem.

"Adenan urged me to prove my claims that DAP would abolish GST in Sarawak if DAP wins in the Sarawak election on May 7," he said in a statement.

"I have never made such a claim on behalf of DAP," he added.

Lim dared Adenan to show proof that he had made such claims to abolish the GST in Sarawak if the party wins the state polls.

"If he cannot show proof, Adenan has shown that he is not trustworthy, when he is willing to abuse his powers to prevent opposition leaders from peninsular Malaysia to enter Sarawak and is now making false claims," he said.

Lim said the Penang government paid RM20 million annually to the federal government when its two local councils – Majlis Bandaraya Pulau Pinang(MBPP) and Majlis Perbandaran Seberang Perai (MPSP) – absorbed the GST cost on the people’s behalf.

"I have never said that DAP would abolish GST in Sarawak if DAP wins the state election.

"I said we should punish BN and Adenan for allowing GST to be implemented and bring hardship to the people," said Lim.

"GST is so cruel by taxing poor people together with the rich, but even state governments and local councils have to pay GST for road and public work projects," he added.

"GST is a federal law and can only be abolished by Parliament, not state governments," he said.

He said Adenan must bear full responsibility for the implementation of GST in Sarawak, adding that the latter had supported the controversial ruling imposed since April 2014.

"His 25 BN Sarawak MPs also voted in support of the GST law in Parliament."

Lim said Penang could not abolish the GST but must pay the taxes on behalf of the people.

As a result of the move, Penang's two local councils – MBPP and MPSP – have to come up with an extra RM20 million annually in making GST payments to the federal government.

"Such payments contribute towards the RM39 billion of GST payments collected annually by the federal government that saved the federal government from bankruptcy as a result of BN’s failed policies, misrule and mismanagement as well as the various financial scandals such as the RM50 billion 1MDB scandal," Lim said.