Prime Minister Najib Abdul Razak says he is still having internal discussions about what issues to raise when he meets US president Donald Trump next month.

However, he said one of the main topics will be the fight against the terrorist Islamic State (IS) group.

"I will have a press conference before I go. I'm in the process of having internal discussions.

"But one of the main topics will be our fight against extremism and also the role Malaysia is playing, in making Southeast Asia a zone of peace. 

"(We'll also talk about) how to improve our economic relationship with the US," Najib said at a press conference in Kuala Lumpur today.

Najib is scheduled to meet Trump on Sept 12.

The Wall Street Journal claimed that sources close to Najib have said that the prime minister will use the meeting to "play down the possibility of further investigations" by the US on the 1MDB scandal.

The US government is currently carrying out criminal investigations into the 1MDB scandal.

The US Department of Justice has also filed civil forfeiture suits to seize assets it claims were purchased using misappropriated 1MDB funds.