* Glencore to retain Mopani output buying rights until debt repaid

* Zambia to seek new investor to finance Mopani expansion

* Expects to repay loan in 10-17 years depending on copper prices

LUSAKA, Jan 19 (Reuters) - Zambia's state mining investment arm ZCCM-IH has agreed to buy Glencore's majority stake in Mopani Copper Mines in a $1.5 billion deal funded by debt and will seek a new investor, the government said on Tuesday.

The sale follows Glencore's attempt to suspend operations at Mopani last year because of low copper prices and COVID-19 disruptions, prompting a government threat to revoke the company's mining licences.

Zambia defaulted on a debt payment in November, becoming Africa's first pandemic-era sovereign default, but will take on more debt to finance the Mopani deal.

The takeover coincides with Zambia's preparations for elections in August, with President Edgar Lungu courting voters in the copper belt. More than 15,000 workers would have lost their jobs if the mine was closed, Mines Minister Richard Musukwa said at a ceremony in Lusaka to mark the deal.

Glencore said that ZCCM-IH will borrow the $1.5 billion from Carlisa Investments Corp, a British Virgin Islands-based company through which Glencore holds its stake, and other unspecified members of the Glencore group.

Under the deal, ZCCM-IH will acquire the remaining 90% of Mopani from Carlisa, giving it full control of the company for an indicative $1.

Glencore will retain buying rights for Mopani's copper output until the transaction debt has been repaid. ZCCM-IH will repay the loan principal by giving Glencore creditors 3% of Mopani's gross revenue from 2021-2023 and 10-17.5% of Mopani's gross revenue from then on.

ZCCM-IH will also owe quarterly interest of LIBOR plus 3%.

Asked how Zambia can afford to take on more debt, a mines ministry official said: "It's not sitting on the ministry of finance. The company is able to pay on its own."

Musukwa said ZCCM-IH will repay the loan in 10-17 years depending on copper prices, which are currently near their highest in eight years at about $8,000 a tonne.

SUSTAINABLE DEBT?

However, the Glencore transaction could compromise Zambia's drive for debt sustainability required as part of any support from the International Monetary Fund (IMF).

"If another $1.5 billion is added to existing debts, it will only make the solvency targets in the (expected) IMF programme more difficult to hit in 2-3 years' time, potentially increasing the need for haircuts on other debts," said an emerging markets debt specialist who has followed Zambia's default.

Mines Minister Musukwa said the country will try to attract a new investor in Mopani, adding that companies from Britain, Canada, China, South Africa, Turkey and Qatar have expressed interest. ZCCM-IH needs about $300 million to complete expansion projects started by Glencore, he added.

Mopani produced 34,479 tonnes of copper last year, up 14.6% from 2019, and the expansion projects will boost output beyond 150,000 tonnes a year, Musukwa said without specifying a timeline.

Analysts said the deal is a positive for Glencore, which will secure its exit from Zambia while maintaining control of Mopani's copper.

"Zambia is not the easiest place to do business at the moment and that has probably stymied a lot of investor interest," said Liberum mining analyst Ben Davis.

"At these commodity prices, all assets are good assets, but it hasn't been that great for Glencore over the past few years."

Glencore said it holds 73% of Mopani through an 81.2% stake in Carlisa. First Quantum Minerals, which previously held 16.9% of Mopani, did not immediately respond to a request for comment.

(Reporting by Chris Mfula in Lusaka Additional reporting by Zandi Shabalala in London and Joe Bavier in Johannesburg Writing by Helen Reid in Johannesburg Editing by Susan Fenton and David Goodman)