Two members of former Kazakh president Nursultan Nazarbayev's extended family have resigned from the leadership of state oil and gas shipping companies, the Central Asian nation's sovereign fund said on Saturday.

Nazarbayev, Kazakhstan's leader for three decades before his resignation in 2019, retained sweeping powers until last week, when his successor Kassym-Jomart Tokayev took over from Nazarbayev as security council chairman amid violent unrest.

The 81-year-old former leader has not appeared in public since the protests erupted on Jan. 4, and Tokayev's critical comments about him have prompted suggestions the two had fallen out before Tokayev sidelined his former patron.

On Saturday, the sovereign fund Samruk-Kazyna said in a statement that Kairat Sharipbayev and Dimash Dossanov had quit as chief executives of state oil pipeline firm KazTransOil and natural gas pipeline operator QazaqGaz respectively.

Sharipbayev is married to the former president's eldest daughter Dariga Nazarbayeva, her son has said on social media. Neither Sharipbayev nor Dariga Nazarbayeva have commented on their relationship. Dossanov is the husband of Aliya Nazarbayeva, Nazarbayev's youngest daughter.

Samruk-Kazyna gave no reasons for their resignations.

Tokayev said this week he wanted Nazarbayev's associates to share their wealth with the public by making regular donations to a new charity foundation.

Last week's protests in the oil-rich nation were triggered by a jump in the price of car fuel in the western Mangistau province.

On Saturday, the authorities said they had detained a deputy energy minister and several other officials who they believe were responsible for the "unjustified" price increase.

(Reporting by Tamara Vaal; Writing by Olzhas Auyezov; Editing by Ros Russell)