The United States said Tuesday it is sending a top envoy to Libya as it voiced 'regret' Tuesday that a US comment taken by Libyan leader Moamer Kadhafi as an insult had harmed ties with the oil-rich country. Libya's National Oil Corporation last week warned US oil firms of possible 'repercussions' over a reaction by State Department spokesman Philip Crowley to a call by Kadhafi last month for jihad against Switzerland. 'I should have focused solely on our concern about the term jihad, which has since been clarified by the Libyan government,' Crowley told reporters in remarks that fell short of an apology. 'I understand my personal comments were perceived as a personal attack on the president... These comments do not reflect US policy and were not intended to offend. I apologize if they were taken that way,' he said. 'I regret that my comments have become an obstacle to further progress in our bilateral relationship,' said the spokesman for US Secretary of State Hillary Clinton. The row comes as US-Libya ties have been improving since Kadhafi in 2003 renounced the pursuit of weapons of mass destruction and agreed to compensate families of the victims of the 1988 plane bombing over Lockerbie, Scotland. Crowley said he and Jeffrey Feltman, the US assistant secretary of state for Near East Affairs, had made the US position clear in their meeting last Friday in Washington with Libya's ambassador. The spokesman added that Feltman would now travel to Tripoli next week for bilateral consultations. 'As I told the (Libyan) ambassador, I hope we can use ongoing dialogue at high levels to continue to advance the US-Libyan relationship,' Crowley said. Kadhafi's call for holy war and economic boycott came on February 25 in response to a Swiss ban on the construction of minarets. The following day, Crowley said: 'I saw that (jihad) report and it just brought me back to the day of September, one of the more memorable sessions of the UN General Assembly that I can recall. 'Lots of words and lots of papers flying all over the place and not necessarily a lot of sense,' Crowley said. Kadhafi took the comment as a personal insult. Libya first summoned the US charge d'affaires in Tripoli and Libya's National Oil Corporation last Thursday called in US oil firms to express 'indignation' over the remark. NOC president Chokri Ghanem said the firms had been advised of 'the negative repercussions which such remarks could have on economic relations between the two countries.' According to Ghanem, the American firms, including ExxonMobil, wrote to the US State Department to protest that such remarks 'could have negative effects on their interests in Libya.' Kadhafi's call meanwhile marked a new low in Libyan-Swiss ties, which soured in July 2008 when Kadhafi's son Hannibal and his wife were arrested and briefly held in Geneva after two domestic workers complained they had mistreated them. The row worsened when Libya swiftly stopped two Swiss businessmen, Rashid Hamdani and Max Goeldi, from leaving its territory. Crowley said Washington took no position on the Libya-Swiss dispute other 'than to register our concern' about the two Swiss citizens, one of whom he said has been released on humanitarian grounds. 