UPDATE 3-Nigerian rebels halt offensive, seek peace talks

* MEND says ceasefire a goodwill gesture for Okah's release

* Government welcomes news, army maintains own ceasefire

* Oil markets take wait-and-see attitude

* Rebels demand military withdraw from parts of Niger Delta

(Adds government comment, paragraphs 11-12)

By Austin Ekeinde

PORT HARCOURT, Nigeria, July 15 (Reuters) - A Nigerian militant group on Wednesday declared a 60-day ceasefire in its offensive against the country's oil industry to provide a chance for peace talks with the government.

The Movement for the Emancipation of the Niger Delta (MEND), whose attacks have cut around 300,000 barrels per day of Nigeria's oil output since May, said its decision was also a goodwill gesture for the release of rebel leader Henry Okah on Monday.