Nigeria's secret police on Thursday issued a warning against what it called "subversive elements" seeking to foment violence in the run-up to next year's general election.
The Department of State Services (DSS) said it had been made aware of "incessant provocative statements by some Nigerians threatening violence ahead of the 2015 general elections".
No examples were given but it came as Nigeria's main opposition All Progressives Congress (APC) party issued a strongly worded statement in relation to simmering tensions in the southern, oil-producing state of Rivers.
DSS spokeswoman Marilyn Ogar called the statements "offensive, misguided and directed at stirring hate".
"This service and other law enforcement agencies have the mandate to protect the country and its citizens," she said.
"We therefore warn all subversive elements that are bent on promoting divisive and disruptive agenda to desist from such, as the full weight of the law shall henceforth be brought to bear accordingly."
The APC said separately that a "culture of lawlessness and impunity" had been promoted and supported by the presidency in Rivers since last February and accused the state police commissioner of being a "de facto military governor".
In a statement after a national executive committee meeting, it alleged police chief Joseph Mbu had cracked down heavily on peaceful APC rallies but done nothing against similar events for the ruling party.
Mbu is widely seen by the opposition as loyal to the president.
If the situation continued, the APC said it would have no option but to call on its members in Rivers and across the country "to take whatever steps that are necessary to protect their lives and property".
The party also called for its members in parliament to block government proposals and approval of the 2014 federal budget "until the rule of law and constitutionalism is restored".
Rivers' high-profile governor Rotimi Amaechi was one of five who defected from the ruling Peoples Democratic Party (PDP) last November.
That prompted 37 lawmakers in the lower chamber National Assembly to follow suit and lose President Goodluck Jonathan his parliamentary majority.
The outspoken Amaechi has claimed Jonathan has done nothing for Rivers and is angered that millions of dollars in revenue from a disputed oil well has gone to the president's home state of Bayelsa next door.