TOKYO (AFP) - Japan, reeling from the murder of two nationals by Islamic State in Iraq and Syria (ISIS) extremists, will offer an extra US$15 million (S$20.3 million) in aid to fight terrorism in Middle East and Africa, a report said on Sunday.

Japan hopes to demonstrate its resolve not to cave in to terrorism with the fresh assistance, which will be announced at a global counter-terrorism conference starting on Wednesday in Washington, the Sankei Shimbun said.

It said the money would be distributed through international organisations to affected regions, including countries bordering Syria and Iraq. Large parts of those countries are controlled by ISIS militants.

Prime Minister Shinzo Abe has come in for criticism over the timing of an earlier US$200 million Japanese pledge to help refugees fleeing ISIS-controlled areas, and the comments he made.

Abe announced the aid in Egypt on Jan 17, saying Japan would "help curb the threat" of ISIS and give the money "for those countries contending with" the militants.

The announcement was followed by the hostage drama, with the militants demanding the same sum in exchange for a captured Japanese contractor and a journalist.

The militants later changed their demand to the release of a death row inmate from a Jordanian prison.

Tokyo pressed Jordan for its help, but the militants eventually announced the killing of the pair as well as a Jordanian airman, along with photos and videos.