Bangladesh is tense ahead of a two-day nationwide strike called by the political opposition. The nation has been swept by violent protests following a bloody attack on an opposition rally that killed nearly 20 people. The main opposition party is accusing the government of involvement in the attack.

Security forces increased their presence in towns and cities across Bangladesh Monday, following two days of violent protests, led by supporters of the opposition Awami League party.

Riot police patrolled the capital, Dhaka, as many schools, colleges and shops closed down out of fear of further clashes.

The protests began Saturday, after grenades were hurled at a rally being addressed by the former prime minister and leader of the Awami League party, Sheikh Hasina Wajed. In addition to those killed, nearly a hundred were injured, including party supporters and some senior officials.

Ms. Hasina escaped unharmed, but her party is angry at what it sees as a bid to kill its leader. On Monday, hundreds gathered outside her home shouting anti-government slogans.

The party's general secretary, Abdul Jalil, accuses the government of complicity. "All these happenings are being done under the government's patronage, and government is doing all these things to crush the secular democratic forces in Bangladesh," he says.

The government has strongly denied the charge and promised a complete investigation.

The Awami League has called a two-day nationwide strike starting Tuesday. The party's youth wing has asked educational institutions to shut down indefinitely.

There have been several bomb blasts in Bangladesh in recent months, some of which have targeted the political opposition. An explosion in June had ripped through a party rally in Sylhet town, and another attack targeted an Awami League mayor in August.

So far, authorities have made no headway in finding those responsible.

U.S. Secretary of State Colin Powell on Sunday strongly denounced Saturday's attack, saying the perpetrators intended to undermine democracy in Bangladesh.