A government minister said Tuesday that Indonesia received warnings from two regional agencies that Monday's undersea earthquake could trigger a tsunami, but that officials did not try to alert threatened communities.

Science and Technology Minister Kusmayanto Kadiman said Indonesia got the bulletins from the Pacific Tsunami Warning Center and Japan's Meteorological Agency, but "we did not announce them."

The warnings were sent about 45 minutes before the tsunami struck.

Even if the government had attempted to phone, radio or e-mail local authorities, it's unclear how the word would have been spread to residents or tourists on the beach, with no alarm systems in place.

Indonesia was the country worst hit by the 2004 Asian tsunami, and Monday's disaster shows how unprepared the sprawling archipelago remains for tsunami triggered by the seismic forces beneath it.

Most people at the devastated Pangandaran beach resort did not feel the magnitude 7.7 quake, and few noticed the ocean receding — a typical pre-tsunami occurrence — because the tide was already low and the effect was not especially pronounced, residents and tourists said Tuesday.

"The police and local officials did not give us any warning whatsoever about the tsunami," said a fisherman who gave only the name Supratu. "Suddenly this big wall of water appeared, and I started screaming and running."

The quake struck at 3:19 p.m., and the Pacific Tsunami Warning Center issued an alert 17 minutes later saying a tsunami was possible.

The first of several waves hit Java's southern coast at about 4:15 p.m., witnesses said.

Indonesia had initially registered the quake at under magnitude 6. By the time government scientists realized its true power, it was too late to warn official offices across the danger zone, said scientist Fauzi, who uses one name.

He said they'd tried to radio the offices, "but there was no way we had the time."

The tsunami killed at least 339 people and destroyed hundreds of homes.

With international help, Indonesia has begun installing a tsunami warning system off Sumatra island's off Aceh province, home to more than 130,000 of the roughly 216,000 victims of the 2004 tsunami.

It plans to roll out the system across the country of 18,000 islands by 2009, officials said Tuesday.

"Setting one up is not as easy as simply lifting your hand," Welfare Minister Aburizal Bakrie told The Associated Press. "We are preparing one, but it is not finished yet."

In Sumatra, two buoys have been placed in the ocean containing equipment able to detect whether a tsunami has been triggered and transmit the information to a land station. However, sirens on beaches or in villages have yet to be set up.

Answering reporters' questions on the lack of a warning, Vice President Jusuf Kalla said there was no need for one because most people fled inland, fearing a tsunami, after feeling the quake.

"After the quake occurred, people ran to the hills, so that is the reason the number of victims is not as great as in Aceh," he said in Jakarta. "So in actual fact, there was a kind of natural early warning system."

However, out of dozens of people interviewed by the AP Tuesday in Pangandaran, only one said he felt a slight tremor. None said there was a mass movement of people to higher ground before the tsunami struck.

In two other countries hit by the 2004 tsunami, progress toward warning systems has been quicker.

Thailand, popular with foreign tourists, has built warning towers on beaches across its southern coast to blare sirens and broadcast evacuation warnings in several languages if regional agencies issue warnings.

Malaysia has positioned two buoys off its shores to give at least an hour's warning to coastal communities, and is capable of transmitting tsunami alerts to the public by TV, radio and mobile phone text messages, officials said.

Sri Lanka has yet to install its own system, but relies on warnings sent by the Hawaii-based Pacific center — a similar institution to Japan's — an official said.

Under Sri Lanka's plan information is passed to villages by phone or national media. Most Buddhist shrines, Hindu temples and Muslim mosques along its coast have sirens, the official said.