Liberia's interim president has expressed regret for his country's part in Sierra Leone's civil war.
Sierra Leone rebels were notorious for brutality towards civilians
On a one-day visit to Sierra Leone, Gyude Bryant said it was time for the two states to put the past behind them.
His predecessor Charles Taylor, now living in exile, is currently appealing against war crimes charges laid by Sierra Leone's UN-backed court.
Meanwhile, UN sanctions against Liberia are to stay in place for the time being, Security Council members have said.
The UN imposed an arms embargo in 2001 to try to prevent Mr Taylor from supporting rebels in neighbouring Sierra Leone.
Mr Bryant, speaking in Freetown after talks with Sierra Leone President Ahmed Tejan Kabbah, told reporters:
"Not all of us endorse what happened. I beg you to forgive us, put away the bitterness of the past and let us live and work together to move our countries forward," he said.
Mr Bryant was inaugurated as interim president last month, as part of an August peace deal to end years of civil war. As part of the deal, Mr Taylor stepped down and is now living in exile in Nigeria.
Mr Taylor has been indicted by the war crimes court on charges supported Sierra Leone's brutal Revolutionary United Front rebels (RUF) - notorious for chopping off the hands, legs, ears and lips of thousands of civilians.
A UN panel has recommended to the Security Council that sanctions against Liberia should be extended.
Its report accused Mr Taylor of absconding with government money and continuing "to divert revenues and assets of the government of Liberia."
The embargo - which is due to run out in May - covers arms, diamonds, logging, and some travel.
On Wednesday, the New York-based Human Rights Watch accused Liberia's northern neighbour, Guinea, - currently a Security Council member - of breaking the arms embargo.
A senior Liberian rebel leader has, however, flatly denied acquiring any weapons from Guinea.