WASHINGTON — Negotiations between the Justice Department and JPMorgan Chase & Co. over the bank’s sale of mortgage-backed securities have hit a stumbling block that has put the talks at risk, a person briefed on the discussions said Tuesday.

A week and a half ago, JPMorgan tentatively agreed to pay $13 billion to settle allegations surrounding the low quality of mortgage-backed securities it sold to mortgage finance companies Fannie Mae and Freddie Mac in the run-up to the 2008 financial crisis. The securities soured after the housing bubble burst in 2007, losing billions of dollars in value.

One of the unresolved issues in the talks: JPMorgan says it should be able to seek money from a receivership involving Washington Mutual, a failed savings and loan that JPMorgan purchased in 2008, said the person, who spoke on condition of anonymity because the source was not authorized to speak by name about the matter.

The receivership is overseen by the Federal Deposit Insurance Corp., the independent agency created by Congress to maintain stability in the banking system. The FDIC’s position is that JPMorgan is responsible for any liabilities regarding the acquisition of Washington Mutual.

The two sides also disagree over whether the bank can face criminal charges. The tentative $13 billion deal only covers civil issues, said the person briefed on the discussions. In a proposal made Sunday night, the bank said it wants to limit any possible criminal exposure to a single ongoing criminal investigation in California, according to the person, who said talks are continuing.