The liquidators of Pioneer Iron and Steel Group have sued Ms Diana Chen Ningning, the granddaughter of a former Chinese minister, her mother and other parties for CNY 4.12 billion (HKD 5.16 billion).They allege this is the amount stolen from the bankrupt company Ms Chen previously owned, a writ filed in the High Court states.

Ms Chen, dubbed the "steel princess", is the granddaughter of the late Lu Dong, the Chinese metallurgy minister in the 1960s and 70s. Chen and her mother Lu Hui are jointly ranked 72nd on the 2010 Hurun China Rich List with an estimated USD 1.7 billion.

Baotou Steel's 2012 annual report said that the assets the liquidators seek are shares in Shanghai-listed Inner Mongolia Baotou Steel Rare-Earth Hi-Tech, according to the writ. A Hong Kong company, Pioneer Metals, owns 9.87% of Baotou Steel worth CNY 5.89 billion given the firm's market value of CNY 59.65 billion.

The report said that Chen owns 51.1% of Pioneer Metals, while her mother owns the remainder, corporate records show. Chen is the legal representative of Pioneer Metals, which was founded in 1995 and had registered capital of HKD 135 million.

The liquidators alleged Pioneer Iron and Steel should rightfully own 70 per cent of Pioneer Metals, which means Pioneer Iron and Steel should indirectly own 6.9 per cent of Baotou Steel, a stake worth 4.12 billion yuan based on Baotou Steel's market capitalisation yesterday. The liquidators are seeking to recover this 70 per cent stake in Pioneer Metals, which they alleged has been illegally transferred to Chen and her mother, the writ states.