UPDATE 1-S.Africa, Eq. Guinea eye tighter ties on Zuma trip

* Visit aimed at strengthening economic, diplomatic ties

* Eq. Guinea says Zuma was to review energy project

* Meeting coincides with release of mercenaries

(Updates with South African statement)

MALABO, Nov 4 (Reuters) - South African President Jacob Zuma sought to strengthen economic and diplomatic ties with oil heavyweight Equatorial Guinea during a visit on Wednesday, his office said in a statement.

Zuma's visit coincided with Equatoguinean President Teodoro Obiang Nguema Mbasogo's release of four South African mercenaries jailed for a foiled 2004 coup led by former British special forces officer Simon Mann, who was also pardoned.

"We are prepared to do what we must to ensure that our nations work hand in hand in promoting development, peace and prosperity for our people," Zuma said in the statement.

Equatorial Guinea said earlier in the day Zuma was to visit the island capital Malabo to "inspect the energy project, hold face-to-face meetings with the government and sign bilateral agreements between the two countries."