"The most worrisome risk is a contraction of the global economy," Abe told a news conference after chairing a G7 summit that declared "global growth is our urgent priority".
Drawing repeated parallels to the global financial crisis that followed the 2008 Lehman bankruptcy, Abe said: "There is a risk of the global economy falling into crisis if appropriate policy responses are not made".
For Japan's part, Abe vowed to "reignite powerfully the engine of Abenomics," referring to his growth and reflation policies.
He said he will decide before a planned summer election whether to raise the national sales tax again.
Government sources told Reuters on Friday the premier will for a second time delay the tax hike as the threat of deflation re-emerges and he prepares to face voters.
(Reporting by Tetsushi Kajimoto; Writing by William Mallard and Michael Perry)
