Washington, Oct 18 (IANS): US President Donald Trump's administration has barred American aid groups from travelling to North Korea as it pressures Pyongyang to dismantle the countrys nuclear weapons programme.

Sanctions imposed by the UN last year have already forced aid groups to severely limit some activities, such as shipping farming equipment into the country, The New York Times reported on Wednesday.

North Korea is one of the world's poorest nations, and its citizens grapple with food shortages.

The moves by the administration seek to tighten sanctions as part of its maximum-pressure campaign during nuclear negotiations, as well as sever non-government exchanges between Americans and North Koreans.

Since last month, the State Department has refused to grant special permission to aid workers to travel to North Korea.

It had done so in some cases in the year since the Trump administration enacted a general ban in September 2017 on Americans travelling to North Korea.

Asked for a comment, the State Department told The New York Times that it was still reviewing exceptions to the general travel ban "on a case-by-case basis, taking into account a range of factors".

Last year's travel ban was issued after an American student, Otto F. Warmbier, died as a result of brain damage suffered in a North Korean prison. Warmbier was arrested in 2016 while on a tour in Pyongyang.