Charles Taylor's former deputy has begun testifying at the ousted Liberian leader's war crimes trial before a U.N.-backed court in The Hague.

Moses Blah, who was Taylor's vice president, is expected to testify at length about how Taylor allegedly directed the actions of rebels in neighboring Sierra Leone during that state's 10-year civil war - a conflict marked by extreme brutality.

Taylor says he is not guilty of the charges against him - murder, rape, torture, recruiting child soldiers and pillaging Sierra Leone's towns and villages. The Liberian president, who seized power in Monrovia in an earlier military campaign, was forced to leave his homeland for exile in Nigeria in 2003, a year after the conflict in Sierra Leone finally ended.

Taylor is accused of supplying weapons to Sierra Leone's notorious Revolutionary United Front fighters, in return for so-called "blood diamonds" supplied by the RUF.

Former Vice President Moses Blah also served briefly as Liberia's interim president following Taylor's departure. He began his testimony Wednesday by recalling how rebel fighters addressed Taylor as "chief." The 61-year-old Blah is said to have decided to appear in open court despite receiving death threats. He is expected to testify for several days.

One account from the court in the Dutch capital says neither Taylor, who is 59, nor Blah, who walks with a cane, looked at each other as the witness took the stand.

Blah is the highest-ranking witness to testify against Taylor, who is the first former African head of state to face international charges of war crimes and crimes against humanity. Previous testimony has described gruesome practices, including cannibalism and mutilation of civilians, that occurred during Sierra Leone's civil war. Blah is the 27th of 72 witnesses the prosecution expects to call.

The U.N.-backed Special Court for Sierra Leone, which is prosecuting Taylor, moved proceedings from Freetown to The Hague to reduce chances of sparking unrest in the west African state or in Liberia, which borders Sierra Leone on the east.

Some information for this report was provided by AFP, AP and Reuters.