Four Yemenis carrying hand grenades and guns were arrested near the U.S. embassy in the Yemeni capital Sanaa, the Interior Ministry said on Tuesday, Reuters reported.
A Ministry statement said the four, aged between 20 and 33, had hand grenades, automatic weapons and ammunition. It did not say when they were arrested.
"The four were detained for questioning especially because they were caught in an area near the American embassy," it said.
The ministry said the four were residents of a town called Damaj in the northern province of Saada, where the government is battling a revolt by Shi'ite Muslims of the Zaydi sect.
The Arab world's poorest country is also battling a wave of al Qaeda attacks and rising secessionist sentiment in the south.
Twin suicide car bombings outside the U.S. embassy in Sanaa a year ago killed 16 people. Al Qaeda claimed responsibility.
International concern over Yemen has been heightened because instability there could endanger neighbours including oil-rich Saudi Arabia and complicate efforts to combat al Qaeda and piracy in the Gulf of Aden.
The United States on Sunday offered to help Yemen in its "fight against terrorism". U.S. President Barack Obama said in a letter to Yemeni President Ali Abdullah Saleh that the United States will "stand beside Yemen, its unity, security and stability".