A strong earthquake struck Friday off the coast of northeastern Japan in the same region that was hit by a massive earthquake and tsunami last year. Tokyo high-rises swayed for several minutes, one city reported a small tsunami and at least two people were reported injured.

The Japan Meteorological Agency said the earthquake had a preliminary magnitude of 7.3 and struck in the Pacific Ocean off the coast of Miyagi prefecture at 5:18 p.m. local time. The epicentre was 10 kilometres beneath the seabed and 240 kilometres offshore.

After the quake, authorities issued a warning that a tsunami potentially as high as two metres could hit. Ishinomaki, a city in Miyagi, reported that a tsunami of one metre hit at 6:02 p.m. The tsunami warning was subsequently cancelled two hours after the quake occurred

Aiko Hibiya, a volunteer for the recovery in Minami-Sanriku, a coastal town devastated by last year's tsunami, said she was at a friend's temporary housing when the quake struck.

"It shook for such a long time," she said.

She said other volunteers who had been in coastal areas were evacuated to a square and a parking lot and were waiting for the tsunami warnings to be lifted.

Miyagi prefectural police said there were no immediate reports of damage from the quake or tsunami, although traffic was being stopped in some places to check on roads.

Sirens whooped along the coast as people ran for higher ground, but the Pacific Tsunami Warning Center said there was no risk of a widespread tsunami.

A 75-year-old woman fell and was injured while evacuating to flee from the tsunami, public television broadcaster NHK reported. It said a child was reportedly injured in the Miyagi city of Sendai. Miyagi police said they could not confirm those reports.

Shortly before the earthquake struck, NHK broke off regular programming to warn that a strong quake was due to hit. Afterward, the announcer repeatedly urged all near the coast to flee to higher ground.

The Meteorological Agency has an early warning system that, using data from seismographs scattered across Japan, enables it to provide advance warning of the estimated intensity and timing of a major quake. The warning for Friday's quake was issued six minutes before it struck, according to an unnamed official from the Meteorological Agency, who spoke on national television more than an hour after the quake.

He continued to warn people to stay away from the coast.

"Please take all precautions. Please stay on higher ground," he said.

The tsunami alert extended from the tip of the main island of Honshu nearly down to Tokyo, though the warning for the area most likely to be hit was only for the Miyagi coast.

The magnitude-9.0 earthquake and ensuing tsunami that slammed into northeastern Japan on March 11, 2011, killed or left missing some 19,000 people, devastating much of the coast. All but two of Japan's nuclear plants were shut down for checks after the earthquake and tsunami caused meltdowns at the Fukushima Daiichi nuclear plant in the worst nuclear disaster since the 1986 Chornobyl disaster.

Immediately following Friday's quake, there were no problems at any of the nuclear plants operated by Fukushima Daiichi operator Tokyo Electric Power Co., said a TEPCO spokesman, Takeo Iwamoto.

All Nippon Airways spokesman Takuya Taniguchi said government officials were checking on the runways at Sendai airport. The two jets that were in the air went to other airports and all seven flights scheduled to go to Sendai for the day were cancelled, he said.