The pipelines will be jointly controlled by the two companies, they said in a joint statement.
Italy imports more than 90% of its overall gas needs and Algerian gas currently accounts for around 30% of flows.
“This transaction allows us to free up new resources to be used on our energy transition path,” Eni Chief Executive Claudio Descalzi said.
Eni is working on spinning off a series of oil and gas operations into new joint ventures to help reduce debt and fund its shift to low-carbon energy.
Snam, which owns a 20% stake in the TAP pipeline that carries Azeri gas into Italy, makes most of its money from managing Italy’s gas transport grid.
It has pledged to spend more on new green business lines such as hydrogen and, like other gas grid operators in Europe, is upgrading its gas network to be hydrogen ready.
“In the future, North Africa could also become a hub for producing solar energy and green hydrogen,” Snam CEO Marco Alvera said.
The pipeline companies involved in the deal posted net income of around 90 million euros in 2020.
($1 = 0.8836 euros)