Israel has taken delivery of two German submarines ordered four years ago, a military spokesman said on Tuesday.
"We have received two Dolphin-class submarines built in Germany," he said, on condition of anonymity.
The submarines, called U212s, can launch cruise missiles carrying nuclear warheads, although when it confirmed the sale in 2006 the German government said the two vessels were not equipped to carry nuclear weapons.
The subs were ordered in 2005 and delivery was initially expected in 2010.
Including the two new ones, Israel has five German submarines -- the most expensive weapon platforms in Israel's arsenal.
Germany, which believes it has a historic responsibility to help Israel because of the mass murder of Jews in World War II, donated the first two submarines after the 1991 Gulf War.
It split the cost of the third with the Jewish state.
According to Jane's Defence Weekly, the U212s are designed for a crew of 35, have a range of 4,500 kilometres (2,810 miles) and can launch cruise missiles carrying nuclear warheads.
Israeli media have written that the Dolphin submarine could be key in any attack on arch-foe Iran's controversial nuclear sites.
An Israeli submarine recently used the Suez Canal for the first time in June, escorted by Egyptian navy vessels, in what Israeli media said was intended as a message to Iran.
Widely considered the Middle East's sole if undeclared nuclear power, Israel suspects Iran of trying to develop atomic weapons under the guise of a civilian nuclear programme, a charge Tehran denies.