The Barisan Nasional (BN) machinery for the Permatang Pauh parliamentary by-election must avoid disunity among component parties, said UMNO vice president Datuk Seri Hishammuddin Tun Hussein.

"Ensure that the BN coalition doesn't become disunited; don't be taken in by those who want to instigate, belittle our leadership, dismiss our achievements, more so in Permatang Pauh," he said.

He told reporters this when met at the Kuala Mengkuang polling centre here Friday.

He noted that the BN election machinery in Permatang Pauh had seen seven general elections and by-elections since 1999 and believe it would maintain the harmony and not feel pressured to perform well in the latest by-election.

"They never give up; despite the seven elections, their spirit never waned. In politics, nothing is impossible, we hope our machinery would surge on with their extraordinary efforts," he said. On the absence of a manifesto by Parti Keadilan Rakyat (PKR), in contrast to the BN, Hishammuddin said it was probably because the party could not fulfill the pledges.

"If it is in 'black and white', would be difficult to escape or twist any issue. I have not seen any change in Permatang Pauh after seven elections. So even if you make a manifesto, no one would believe.

"See for yourself, what development have they brought, what have they implemented," he said.

On Penang Chief Minister Lim Guan Eng's statement that he would look after the Permatang Pauh constituency if PKR candidate Dr Wan Azizah wins, Hishammuddin said Lim appeared to lack confidence in the party's president.

"If the chief minister wants to look after Permatang Pauh, he might as well contest here. I assure that should Suhaimi win, he will represent the federal government here. He won't be a loner," he said.

The Permatang Pauh by-election on May 7 would be a contest among four candidates comprising BN's Suhaimi Sabudin, Datuk Seri Dr Wan Azizah Wan Ismail, Azman Shah Othman (Parti Rakyat Malaysia) and Salleh Isahak (Independent).

Meanwhile, Hishammuddin who is also Defence Minister, said the people must focus on strengthening the economy, unity and security for the prosperity of the country.

"Politics is politics, but our country needs to lean on a strong economy, unity and security. Many countries had let emotions rule them and look at what happened to their economy, security...

"In the end, innocent people became victims, immigrants, killed, and beggers in their own country," he said.