SAN FRANCISCO — Google is facing increased scrutiny by lawmakers in Washington over its size and influence. Now, a research scientist who recently resigned from the company in protest is urging them on.

In a harshly worded letter sent this week, the former employee, Jack Poulson, criticized Google’s handling of a project to build a version of its search engine that would be acceptable to the government of China. He said the project was a “catastrophic failure of the internal privacy review process.”

He said lawmakers should increase transparency and oversight of the company and technology industry, saying that there is a “broad pattern of unaccountable decision making.”

Dr. Poulson left the company after news articles revealed the existence of the project last month. It was first reported on by the Intercept news site.