WASHINGTON: Pakistan's ambassador to the United States Sherry Rehman branded as "unhelpful" U.S. Defense Secretary Leon Panetta's latest stab at Islamabad's failure to tackle militant safe havens, saying it would make it harder for the two countries to narrow their differences.

Panetta, speaking in Kabul on Thursday, said the United States was reaching the limits of its patience with Pakistan because of the safe havens the country offered to insurgents fighting in neighboring Afghanistan.

"It adds an unhelpful twist to the process and leaves little oxygen for those of us seeking to break a stalemate," Pakistan's envoy, Sherry Rehman, said in a statement. . Reuters