BEIRUT ( AP) — Syrian forces have detained and tortured children as young as 13 as the government tries to crush an uprising that began nearly 11 months ago, Human Rights Watch said today as fresh clashes erupted between regime troops and rebels in the country’s south.

Today’s fighting in Jassem, in the southern province of Daraa, killed at least one soldier and wounded five, according to the British-based Syrian Observatory for Human Rights.

The Syrian conflict has grown more militarized in recent months as army defectors joined the uprising against President Bashar Assad and formed a guerrilla force. The insurgency in turn brings a heavier regime assault on areas where the defectors are holed up.

The U.N. estimated in January that at least 5,400 people have been killed in the crackdown, including soldiers who defected and those who refused orders to fire on civilians.

But the U. N. has been unable to update its tally since, because the chaos in the country makes it difficult to cross-check the latest figures.

Today, the New York-based Human Rights Watch issued a report in which it said it has documented at least 12 cases of children detained under “inhumane” conditions and tortured, as well as children shot while in their homes or on the street.