Federal securities regulators plan to warn several major banks that they intend to sue them over mortgage-related actions linked to the financial crisis, according to people familiar with the matter.

The move would mark a stepped-up regulatory effort to hold Wall Street accountable for its sale of bonds linked to subprime mortgages in 2007 and 2008. At issue is whether the banks misrepresented the poor quality of loan pools they bundled and sold to investors, the people said.

It...