Kosteniuk, a Russian competing under the FIDE flag, was awarded €15,000 (£13,200/$16,100) as she finished with an overall score of 7.5.

The win in Munich also sees her win 160 Grand Prix points.

India's Koneru Humpy looked as if she could snatch a late lead after beating Kosteniuk in the penultimate day of competition.

However, she fell to an unexpected defeat to Tan Zhongyi of China who put in a formidable defensive display.

The result meant Humpy took silver with seven points while Georgia's Nana Dzagnidze rounded out the podium on 6.5 with three wins and a single defeat from the 11 rounds.

Humpy and Dzagnidze will take home €12,000 (£10,500/$12,800) and €10,000 (£8,800/$10,700), respectively.

German Chess Federation President Ullrich Krause and European Chess Union vice-president Alojzije Jankovic performed the ceremonial first moves of the final round in the games of Poland's Alina Kashlinskaya versus Germany's Elisabeth Paehtz and Zhu against Kosteniuk, respectively.

Zhu and Kosteniuk's fixture was the last one of the tournament in Germany.

The game began with a complicated Nimzo-Indian variation.

The position remained balanced for most of the game until Kosteniuk blundered with moving her knight into a vulnerable position.

Zhu capitalised and took the piece and a bishop on the next turn.

The sequence pushed momentum into the Chinese player's favour and Kosteniuk was eventually forced to retire.

Last year, Kosteniuk was one of 43 elite Russian chess players that signed an open letter to Russian President Vladimir Putin protesting against the 2022 Russian invasion of Ukraine.