Bahrain's Foreign Ministry has said a top U.S. diplomat "is unwelcome and should immediately leave the country."
Assistant Secretary of State Tom Malinowski oversees democracy, human rights and labor issues. On Sunday, he met with Al Wifaq, a Shiite opposition group. Bahrain's Foreign Ministry said the meeting was "indicative of an approach which discriminates amongst the people of this one nation."
At the U.S. State Department in Washington, spokeswoman Jen Psaki said Malinowski was still in Bahrain.
"Our team ... is in close touch on the ground to figure out with the government to figure out exactly what's happened here," she said.
Psaki added that Malinowski was in Bahrain to "reaffirm and strengthen our bilateral ties and to support His Royal Majesty King Hamad's reform and reconciliation efforts at an important time."
The Associated Press offers the background to the story:
"Bahrain, a tiny island nation that is home to the U.S. Navy's 5th Fleet, has been roiled by near-daily protests by Shiites seeking greater political rights and inspired by the Arab Spring wave of revolutions since early 2011. The Bahrain government moved to crush the uprising, which threatened to spill into neighboring Saudi Arabia and other Gulf countries with Shiite populations, with the help of regional Gulf Arab forces."
The AP adds that political talks have failed to close the divide between Bahrain's Sunni monarchy and the country's majority Shiites.