* Worst maritime disaster in Italy since Costa Concordia
* Seven dead, two missing, four injured and in hospital
* Fifty metre-high control tower crashes into sea
* Investigation focusing on ship's engine (Updates with transport minister, number of confirmed dead)
By Paola Balsomini
GENOA, Italy, May 8 (Reuters) - Seven people were killed and two were missing after a container ship crashed into a concrete control tower in the northern Italian port of Genoa, rescuers said on Wednesday.
The tower, which was 50 metres (160 feet) high and looked much like those at airports, collapsed into the sea late on Tuesday after being struck by the vessel, the Jolly Nero.
Among the dead were three of its officers, a coastguard statement said. Divers were searching for two missing people at the site and cranes were sifting through debris along the shore.
The other victims have yet to be identified. Two were recovered on Wednesday from the wreckage of the tower's lift, an fire department spokesman said.
The accident happened as staff were changing shifts and there were 13 people in the tower when it was struck, the coastguard said.
As well as the dead and missing, officials said four other people were injured and had been taken to hospital. Two were seriously hurt and a third had lost a foot, investigators said.
"The main injuries are fractures, crushed body parts, significant traumas," emergency services doctor Andrea Furgani said.
The crash occurred shortly after 11 p.m. (2100 GMT) in calm conditions as the Jolly Nero was manoeuvring out of the port.
Genoa prosecutor Michele Di Lecce has opened an investigation and is focusing on a possible malfunction of the ship's engine, judicial sources said.
In testimony to parliament after visiting the port, Transport Minister Maurizio Lupi also said an engine problem could be behind the incident, which took place in "perfect" weather conditions.
Other causes could have been a human error or problems with tow cables fixed to two tug boats that were accompanying the ship out of the harbour, Lupi said.
The crash is the most serious maritime accident in Italy since the Costa Concordia liner struck a rock and capsized off the island of Giglio in January 2012, killing 32 people.
"There's no logical explanation because two tug boats were moving the ship and there was a port pilot on board and sea conditions were optimal," the head of the Genoa Port Authority, Luigi Merlo, said.
All that was left of the tower was a leaning metal stairway.
The Jolly Nero, which is 238 metres (781 feet) long with a gross tonnage of 40,594 tonnes, is owned by local operator Ignazio Messina and Co.
"A thing like this has never happened, we are devastated," said Stefano Messina, one of the directors of the family-owned firm, who was in tears when he spoke to a local TV channel. (Additional reporting by James Mackenzie, Antonella Cinelli and Steve Scherer; Editing by Louise Ireland and Barry Moody)