TOKYO - NORTH Korea issued a fresh warning on Wednesday to Japan to stay clear of some of the communist country's coastal areas when Pyongyang conducts military exercises this month, the Japan Coast Guard said.

The emailed message was seen as signalling more possible short-range missile tests at a time when North Korea is also thought to be preparing a long-range missile launch into Pacific waters short of Hawaii.

Pyongyang issued navigation bans for 10 ocean areas in the Sea of Japan (East Sea) and the Yellow Sea, citing 'military gunfire and bombardment training,' said Japanese Coast Guard spokesman Go Nagai.

The alert covers the hours 8am to 8pm from Wednesday until July 11, extending by one day the period in a previous warning.

North Korea fired a rocket over Japan on April 5 and conducted its second nuclear test on May 25, before also launching several short-range missiles, earning the isolated state international protests and new UN sanctions.

Washington has said it is ready for the possibility North Korea could fire a long-range missile toward Hawaii, possibly on the July 4 US Independence Day, a scenario reportedly outlined in a Japanese defence ministry paper. -- AFP