Nepal Prime Minister KP Sharma Oli resigned on Tuesday as anti-corruption demonstrators defied an indefinite curfew and clashed with police, a day after 19 people died in violent protests triggered by a social media ban, Reuters reported.

Oli's government lifted the ban after protests intensified on Monday, with police firing tear gas and rubber bullets at protesters trying to storm parliament. Nineteen people were killed and more than 100 injured in the unrest.

But there was no letup in the protests on Tuesday, forcing Oli to quit and plunging Nepal into fresh political uncertainty.

The unrest is the worst in decades in the poor Himalayan country that is wedged between India and China and has struggled with political instability and economic uncertainty since protests led to the abolition of its monarchy in 2008, according to Reuters.

"In view of the adverse situation in the country, I have resigned effective today to facilitate the solution to the problem and to help resolve it politically in accordance with the constitution," Oli said in his resignation letter to President Ramchandra Paudel.