(Refile to correct headline name to Koizumi)

TOKYO (Reuters) -Japan's ruling party executive Shinjiro Koizumi said on Friday that he would immediately order the compilation of a stimulus package if he became the prime minister.

"I'll aim to beef up the underlying strength of the Japanese economy so that growth can be attained even in an era where inflation and higher interest rates co-exist," Koizumi said in a press conference, where he announced his intention to run in the ruling party leadership race later this month.

The ruling Liberal Democratic Party (LDP) is set to elect a new leader on Sept. 27 and by extension the country's next prime minister.

(Reporting by Kentaro Sugiyama and Makiko Yamazaki; Editing by Himani Sarkar)