(CNN)The Trump administration will unveil more tailored restrictions on travelers from certain countries as a replacement to the controversial travel ban, according to a senior administration official.

The new restrictions will vary by country. They could include a ban on travel to the United States, or new restrictions on obtaining a visa for citizens of particular countries.

They would replace the ban on entry by citizens of six Muslim-majority nations, which Trump announced early in his term and later modified.

The policy was under a 90-day review, which expires Sunday. The new measures are expected to take effect by then.