LIMA, Nov 15 (Reuters) - Peru's gross domestic product (GDP) shrank 1.29% in September from the same month last year, the government's INEI statistics agency said on Wednesday, marking a fifth consecutive month of decline and landing well below analysts' expectations.

Analysts polled by Reuters had forecast a contraction of 0.65%.

The figure comes after Adrian Armas, the chief economist of Peru's central bank warned last week that July to September could mark a third straight quarter of economic contraction in the Andean country, the world's second-largest copper producer.

Peru had slid into a technical recession earlier this year after two quarters of negative growth due to the adverse impacts of the El Nino weather phenomenon, lower private investment and lingering effects from earlier social conflicts.

Armas told a conference last week that the central bank's current forecast of 0.9% economic growth over 2023 - down from a prior forecast of 2.2% growth - faces "downward pressure".

Peru's economy ministry had meanwhile flagged a possible turnaround in the fourth quarter as a package of stimulus measures aimed at boosting investments, particularly in the critical mining sector, take effect. (Reporting by Marco Aquino; Writing by Sarah Morland; Editing by Aida Pelaez-Fernandez)