Sierra Leone President Ahmad Tejan Kabbah has threatened to impose a state of emergency if election violence between rival parties does not stop.
Voters showed great enthusiasm for the poll
Two days of clashes have marred campaigning for the second round of Sierra Leone's presidential elections.
In a TV address, Mr Kabbah said the country - which endured a brutal civil war - had suffered too much to allow chaos and civil unrest again.
He urged the two rival candidates to call for calm among their supporters.
"All those responsible for the violence and lawlessness should be prepared for the consequences," President Kabbah warned.
"The government shall not hesitate for one moment to declare a state of public emergency if the current state of intimidation, molestation and violent acts is not stopped immediately."
Police have stepped up their patrols around the capital, Freetown, after firing tear gas to disperse rival supporters who clashed in the streets on Sunday and Monday.
Ernest Bai Koroma topped the first round of the presidential poll
They also fired tear gas in the diamond-rich eastern town of Kono when hundreds of rival supporters clashed. Several people were injured.
Police Inspector General Brima Acha Kamara says all is now very calm.
BBC West Africa correspondent Will Ross says that should a state of emergency be declared it is possible that the presidential run-off election could be postponed or all campaigning banned.
He adds that with both political parties blaming each other for inciting violence in what is a very close contest there is a danger of the violence escalating.
The first round of landmark elections on 11 August was judged free and fair by observers.
The opposition APC candidate, Ernest Bai Koroma, took 44% of the vote in the first round, and the ruling SLPP candidate and Vice-President Solomon Berewa, polled 38%.
But tensions are high ahead of the 8 September second round, with opposition supporters confident of winning.
The APC won control of the national parliament and Mr Koroma has also secured the key support backing of the third placed candidate in the first round presidential poll, Charles Margai, who polled 14%.
Our reporter says suspicions of foul play are inevitable given the closeness of the elections and those who believe the APC candidate is a shoe in for the presidency are suspicious that the governing party would not be willing to give up power.
President Kabbah's speech and threat to declare a state of emergency has increased some people's suspicion, he adds.