DUBAI, June 20 (Reuters) - An effort to restructure debt-burdened Saudi builder Mohammad Al Mojil Group (MMG) was thrown into doubt on Monday when the firm said its board had resigned after three people involved with the company were sentenced to jail.

Last week, Saudi Arabia's stock market regulator fined MMG 1.6 billion riyals ($427 million) and sentenced three people, including founder Mohammad Al-Mojil, to jail on charges of manipulation and fraud relating to the firm's initial public offer of shares.

In a statement on Monday, MMG said the decision by the Committee for the Resolution of Securities Disputes was based on "fundamentally flawed" evidence and had severely hurt the board's ability to run the company.

"The decision to resign is, in part, due to their serious concerns about the unlimited director and executive liabilities in the Kingdom of Saudi Arabia," the statement said, without saying what the company would do next.

(Reporting by Andrew Torchia, editing by Louise Heavens) ((andrew.torchia@thomsonreuters.com; +9715 6681 7277; Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))