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North Korea's economy shrank at its sharpest pace in eight years after a fall global commodity prices hit the value of its coal and iron ore exports.

Gross domestic product fell by 1.1% last year compared to a 1% gain in 2014, according to an estimate from South Korea's central bank.

The Bank of Korea has released the data annually since 1991 using information supplied from sources such as the Ministry of Unification.

North Korea does not publish any data.

The worsening economic picture may put pressure on North Korean leader Kim Jong Un.

Pyongyang is facing heavy international sanctions because of its continued provocations such as missile launches and nuclear threats.

China is North Korea's main trading partner but its demand for raw materials has lessened as it moves away from manufacturing towards a more consumer-oriented economy.

North Korea's exports fell by 14.8% last year in annual terms, mostly due to a slump in mineral product shipments.

Imports slid by 20%, versus an increase of 7.8% in 2014.

However, construction and services are believed to have gained last year.