BERLIN (Reuters) - Lawmakers from Volkswagen's home region called on Wednesday for an inquiry into the sudden departure of the German carmaker's compliance chief last month, saying they were concerned the supervisory board was not overseeing the business effectively.

Christine Hohmann-Dennhardt was hired in late 2015 to help Europe's biggest carmaker reform itself following its diesel emissions cheating scandal. But last month, after little more than a year in the job, she abruptly left.

Some analysts and investors have long questioned whether Volkswagen <VOWG_p.DE>, a business tightly controlled by its founding Porsche-Piech clan and its home state of Lower Saxony, could effectively reform itself.

"(We fear) the state (Lower Saxony) and the supervisory board are only insufficiently carrying out their ownership role and controlling task," lawmaker Mathias Middelberg wrote in a letter to Stephan Weil, the prime minister of Lower Saxony.

Spokespeople for Volkswagen (VW) and Weil did not immediately respond to requests for comment.

Middelberg leads a delegation of 31 Lower Saxony lawmakers from Chancellor Angela Merkel's Christian Democratic Union (CDU) in Germany's lower house of parliament.

Weil sits on VW's 20-strong supervisory board which has the power to appoint and dismiss executives.

In his letter dated Feb. 21 and seen by Reuters, Middelberg referred to media reports that said Hohmann-Dennhardt's role as compliance chief was destined to fail.

Her hiring coincided with the appointment of Manfred Doess as head of legal affairs at VW. Doess is also compliance chief at Porsche SE <PSHG_p.DE>, the holding company of the Porsche-Piech clan.

Middelberg said in his letter that Doess appeared to have more clout in the aftermath of the emissions scandal than Hohmann-Dennhardt even though he was her subordinate.

Middelberg asked Weil to commission independent experts to investigate how the jurisdictions of Doess and Hohmann-Dennhardt were defined, whether a possible conflict of their duties was discussed by the supervisory board and whether the former compliance chief was granted a monthly pension of 8,000 euros ($8,411) in addition to 12 to 15 million euros in severance pay.

Spiegel Online first reported Middelberg's letter.

Germany is holding federal elections in September 2017 and a regional vote in Lower Saxony in January 2018.

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(Reporting by Jan Schwartz and Andreas Cremer; Editing by Mark Potter)