HONOLULU - Hawaii prepared to start evacuations ahead of a tsunami generated by a massive earthquake in Chile, a civil defence official on the U.S. island said on Saturday.

It planned to sound civil defence sirens across the island state at 6 a.m. local time (4 p.m. British time) after the Pacific Tsunami Warning Centre said a tsunami was generated that could cause damage along the coasts of all the Hawaiian islands,

Get off the shore line. We are closing all the beaches and telling people to drive out of the area, said John Cummings, Oahu Civil Defence spokesman.

Buses will patrol beaches and take people to parks in a voluntary process expected to last five hours.

More than an hour before sirens were due to sound lines of cars snaked for blocks from gas stations in Honolulu.

Urgent action should be taken to protect lives and property, the Warning Centre said in a bulletin. All shores are at risk no matter which direction they face.

The centre has issued a Pacific-wide tsunami warning that included Hawaii and stretched across the ocean from South America to the Pacific Rim.

Geophysicist Victor Sardina said the Hawaii-based centre was urging all countries included in the warning to take the threat very seriously.

Everybody is under a warning because the wave, we know, is on its way. Everybody is at risk now, he said in a telephone interview.

The warning follows a huge earthquake in Chile that killed at least 82 people and triggered tsunamis up and down the coast of the earthquake-prone country.

The centre estimates the first tsunami, which is a series of several waves in succession, will hit Hawaii at 11:19 a.m. Hawaii time (9:19 p.m. British time) in the town of Hilo on the Big Island of Hawaii, with waves in Honolulu at 11:52 a.m.

Sardina said the Hawaiian islands could expect waves of six feet (two meters) in some places. Other estimates have been higher but he could not confirm those were likely.

Sardina said the centre was looking at Hilo Bay on Hawaii Island as a worst-case scenario right now.

The shape of the bay favours the waves gaining in height, he said in a telephone interview.

He said California and Alaska could also be affected, but the impact on those coasts should be minimal.

(Reporting by Suzanne Gordon and Ikaika Hussey in Hawaii and Doina Chiacu in Washington; writing by Peter Henderson, editing by Vicki Allen)