Gaddafi’s letter to Obama rejected by US (VIDEO)

The U.S. State Department has rejected a personal letter from Libya's defiant leader, Muammar Gaddafi, to U.S. President Barack Obama, saying Gaddafi must step down.

Gaddafi's three-page, rambling letter to Obama called on the president to stop the "unjust war" against Libya, AP reported.

"You are a man who has enough courage to annul a wrong and mistaken action," Gaddafi wrote in the letter. "I am sure that you are able to shoulder the responsibility for that."

Addressing Obama as "our son," Gaddafi asked the president to halt the NATO-led air campaign, which has been targetting the regime's military infrastructure and weapons stockpiles.

He also wished Obama luck in the upcoming presidential election.

U.S. Secretary of State Hillary Clinton rejected the appeal and said Gaddafi must withdraw his forces and go into exile, Reuters reports.

"Mr. Gaddafi knows what he must do," Clinton said at a news conference. "There needs to be a ceasefire, his forces need to withdraw from the cities that they have forcibly taken at great violence and human cost. There needs to be a decision made about his departure from power and … his departure from Libya."

A U.S. official told Reuters that the White House has received numerous letters from Gaddafi over the years, and this one is not being taken particulary seriously.

Meanwhile, Libyan officials accused British war planes of bombing a Libyan oil field, killing three civilian guards and wounding others, the Press Association reports.

"British warplanes have attacked, have carried out an air strike against the Sarir oil field which killed three oil field guards and other employees at the field were also injured," Libyan Deputy Foreign Minister Khaled Kaim said at a news confernece. "There is no doubt this aggression … is against international law and is not covered by the U.N. resolution."

Britain's Ministry of Defense had no immediate comment on the accusation, Reuters reports.

NATO forces stepped up attacks in Libya on Wednesday, a day after Libyan rebels lashed out at the alliance for being too slow to act and allowing too many civilians to die at the hands of Muammar Gaddafi's forces.

The North Atlantic Treaty Organization jets planned to fly 198 missions over Libya on Wednesday, an increase over 155 flown Tuesday, NATO chief spokeswoman Oana Lungescu said in a statement. The “operational tempo has increased,” under NATO, she said, Bloomberg reported.

"NATO blesses us every now and then with a bombardment here and there, and is letting the people of Misurata die every day," Abdel Fattah Younes, head of the rebel forces told Reuters in Benghazi, the opposition stronghold. "NATO has disappointed us."

Residents of Benghazi have taken to the streets in recent days in growing numbers to protests the NATO strikes, which they say have been ineffective and have killed civilians.

“From Tuesday there have been no air strikes, but they killed our rebels,” said Omar Mustafa, a father of six girls. “We don’t know why NATO is not working."

A coalition led by the United States, France and Britain began air strikes against Gaddafi's forces on March 31 in an effort to protect civilian lives. The bombardment against Gaddafi's tanks and weapons enabled the rebel forces, which have been fighting for control over the country for almost two months, to regroup and reclaim cities in the east.

NATO took command of the military campaign this week and now leads air strikes to enforce a no-fly zone and attack Gaddafi's military infrastructure that could be used to target civilians. The campaign is now focused on Misurata, Libya's third largest city and the site of fierce fighting.

Gaddafi's forces continued their seige on Misurata Wednesday, unleashing mortar rounds, tank fire and artillery shells.