And United Liberal Party Vice president Gabriel Chibambula has resigned to join the UPND.
Mr. Hichilema says if the UPND goes it alone in the 2011 elections,chances of removing the current MMD government are very slim.
He says Zambia needs a united opposition in order to remove the ruling MMD from power in the 2011 tripartite elections.
Mr. Hichilema has since called for unity among Zambians if the country is to achieve the change of government.
Mr. Hichilema says the country has continued to suffer at the hands of the corrupt MMD government.
The UPND leader further stated that the UPND/PF pact is intact despite attacks that from the ruling MMD and its sympathizers.
And ULP vice president Gabriel Chibambula has resigned to join the opposition UPND.
Welcoming Mr. Chibambula into the UPND, party president Hakainde Hichilema said the party needs more people.
Mr. Hichilema indicated that more people are going to join the UPND in the coming weeks.