JOHANNESBURG, May 15 (Reuters) - South African President Cyril Ramaphosa said on Monday the country's non-aligned position did not favour Russia over other states and reiterated its call for a peaceful resolution to the conflict in Ukraine.

His comments in a weekly presidential newsletter came on the heels of U.S. allegations last week that weapons were loaded onto Russian ship Lady R from a naval base in Cape Town late last year, which sparked a diplomatic row.

South African officials swiftly rejected claims made by the U.S. ambassador to South Africa Reuben Brigety, who also said senior U.S. officials had "profound concerns" over South Africa's professed policy of non-alignment and neutrality over Russia's war in Ukraine.

"We do not accept that our non-aligned position favours Russia above other countries. Nor do we accept that it should imperil our relations with other countries," Ramaphosa said.

South Africa would continue to honour international agreements and treaties it is a signatory to and its approach to U.S. allegations of arms shipment would abide by them, he added.

Ramaphosa's office has said no concrete evidence has been provided to support the claims made by the ambassador, but that an inquiry led by a retired judge would look into them.

Several ministers, including the one responsible for arms control, a foreign ministry spokesman and the communications minister have said South Africa had not approved any arms shipment to Russia in December.

Brigety was summoned on Friday to meet South African foreign minister Naledi Pandor and he apologised "unreservedly" to the government and the people of South Africa, a foreign ministry statement said.

"I was grateful for the opportunity to speak with Foreign Minister Pandor... and correct any misimpressions left by my public remarks," Brigety said in a tweet that did not confirm whether he had apologised.

South Africa, which has abstained from voting on U.N. resolutions on Russia's war in Ukraine, says it is impartial but Western countries consider it to be one of Moscow's closest allies on the continent.