The Obama administration is raising the bar for foreigners seeking asylum in the U.S., saying they must now demonstrate “a substantial and realistic possibility” of succeeding with their claims before they can go before a judge, the government’s internal records show.

The documents say the new guidelines are meant to reinforce the government’s standard that allows asylum seekers to initially demonstrate a “significant possibility” they would prevail. The new guidelines are outlined in a Feb. 28 memo sent by John Lafferty, chief of the asylum division at U.S. Citizenship and Immigration Services.

At issue are “credible fear interviews” conducted by federal officials who decide whether to deport the asylum seekers or refer them to immigration judges in the U.S.

Lafferty cited concerns that the government’s asylum standards have “lately been interpreted to require only a minimal or mere possibility of success.” He also linked the changes to a surge in asylum claims. Since fiscal year 2012, he said, his division has seen a 250 percent increase in referrals of immigrants citing “credible fear” of returning to their home countries.

The National Immigrant Youth Alliance, an immigrant rights group that recently obtained a copy of Lafferty’s memo, called the change harsh. A spokesman for USCIS issued a prepared statement Friday, saying the government has long interpreted the law to require applicants to “demonstrate a substantial and realistic possibility of succeeding. The current training guidelines are intended to ensure proper implementation of the statutory standard that governs these screenings.”