U.S. President Barack Obama plans to send 250 more military personnel to Syria, increasing the U.S. presence on the ground there to about 300 troops to help fight Islamic State militants, a U.S. official said on Sunday.

The deployment will come on top of 50 special operations forces whom Obama deployed to Syria last year, two U.S. officials said. One official said the announcement would come in a speech Obama plans to give in Hanover, Germany, on Monday.

The decision, first reported by the Wall Street Journal, confirms an April 1 Reuters report that the Obama administration was considering boosting the number of special operations forces in Syria in hopes of accelerating gains against Islamic State.

Islamic State, also known as ISIS or ISIL, controls the cities of Mosul in Iraq and Raqqa in Syria and is proving a potent threat abroad, claiming credit for major attacks in Paris in November and Brussels in March.

"He intends to put in more ... forces to the tune of 250 in Syria," said one U.S. official, adding he was unable to break down how many of those would be special operations forces and how many might be involved in support activities such as medical and intelligence personnel.