Most border crossings in Liberia have been closed and communities hit by an Ebola outbreak face quarantine to try to halt the spread of the virus.
Screening centres are also being set up at the few major entry points that will remain open, such as the main airport.
Meanwhile, Nigeria largest's airline, Arik Air, has suspended all flights to Liberia and Sierra Leone after a man with Ebola flew to Nigeria last week.
The virus has killed at least 660 people in West Africa since February.
The outbreak began in southern Guinea and spread to Liberia and Sierra Leone. It is the world's deadliest so far.
Nigeria has put all its entry points on red alert after confirming that a Liberian man died of Ebola after arriving at Lagos airport on Tuesday.
Ebola since 1976
Ebola kills up to 90% of those infected, but patients have a better chance of survival if they receive early treatment.
It spreads through contact with an infected person's bodily fluids.
Arik Air said it took the decision to halt flights as a precautionary measure and called for all inbound flights to Nigeria from Ebola-affected countries to be suspended.
"We feel especially compelled to take the business decision to immediately suspend flight services into the two Ebola affected countries due to our interest in the well-being of Nigerians," the airline, which operates routes across West Africa, said in a statement.
In a statement on Sunday night, Liberian President Ellen Johnson Sirleaf said the special Ebola task force she was heading would ensure that "communities that are seriously affected will be quarantined and travels in and out of such communities restricted".
The BBC's Jonathan Paye-Layleh in the capital, Monrovia, says her new orders include strict observation at the international airport of all outgoing and incoming passengers, who are now liable for inspection and testing.
All government facilities and public places are to install public access for washing of hands and all hotels, restaurants, and film centres are to play five-minute information clips on Ebola awareness and prevention.
Over the weekend prominent Liberian doctor Samuel Brisbane died after a three-week battle with the virus.
Two US aid workers are also being treated for Ebola in Liberia, including Dr Kent Brantly, who was the medical director at one of the country's two treatment centres run by the group the Samaritan's Purse.
The other American, Nancy Writebol, works for the Serving in Mission (SIM) as part of the same team.
"It's been a shock to everyone on our team to have two of our players get pounded with the disease," Ken Isaacs, from the Samaritan's Purse in the US, told the Associated Press news agency.
President Johnson Sirleaf urged people to co-operate with health workers and Ebola awareness campaigners.
Last month she warned that anyone caught hiding suspected Ebola patients would be prosecuted.
Experts say the disease creates fear within communities and sick people are often stigmatised.
Liberian Senator Peter Coleman, a doctor and former health minister, told the BBC authorities needed to approach religious leaders to spread the message about Ebola as "people don't seem to believe anything the government now says".
Ebola virus disease (EVD)
- Symptoms include high fever, bleeding and central nervous system damage
- Fatality rate can reach 90%
- Incubation period is two to 21 days
- There is no vaccine or cure
- Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery
- Fruit bats are considered to be virus' natural host