ROME May 17 (Reuters) - Italy and Libya discussed on Tuesday renewing a 2008 accord under which Italy pledged billions of dollars in investments in return for energy contracts and controlling illegal migration from North Africa, Italy's foreign ministry said.

The original deal was struck by then-Italian premier Silvio Berlusconi and former Libyan leader Muammar Gaddafi before Gaddafi was ousted and the country plunged into chaos.

The breakdown of order in Libya, where human traffickers have taken advantage of the turmoil to pack people fleeing war and poverty into unseaworthy boats, has contributed to Europe's worst migration crisis since World War Two.

Talk of the 2008 "friendship pact" was revived by Mohammed Siyala, Foreign Minister in Libya's new U.N.-backed national unity government, and his Italian counterpart Paolo Gentiloni in Rome on Tuesday.

"The two ministers talked ... about the possibility of reactivating the tools set out in the 2008 friendship pact as soon as possible," the Foreign Ministry said in a statement.

The West is counting on the unity government, which arrived in late March, to tackle armed violence, Islamic State militants and stop flows of migrants across the Mediterranean.

European officials are worried about large numbers of would-be migrants building up in Libya, but say the volatility there precludes the kind of deal struck with Turkey to block last year's main entry point to Europe via Greece.

Libya's new leaders still lack effective control over the capital Tripoli, and the country's coast guard has struggled in the past to patrol its waters.

Berlusconi and Gaddafi presented the 2008 pact as compensation for damage inflicted on Libya by Italians during the latter's 1911-1943 colonial rule.

Italy planned at the time to invest $200 million per year in projects including road-building and clearing mines in Libya over 25 years, for a total $5 billion. (Reporting by Isla Binnie, Editing by Angus MacSwan)