ABUJA: The United States and Britain said there were worrying signs of political interference in the counting of Nigeria’s votes on Monday as results from the closest election since the end of military rule in 1999 started to trickle in.

The weekend vote was marred by confusion, technical glitches, arguments and occasional violence but in many places proved to be less chaotic than previous elections in Africa’s most populous nation and biggest economy.

President Goodluck Jonathan against former military ruler Muhammadu Buhari were seeking the votes of an electorate divided along ethnic, regional and religious lines in the nation of 170 million.

Even before preliminary tallies were recorded, the opposition All Progressives Congress (APC) rejected the outcome in Rivers state, headquarters of Africa’s biggest oil industry, and denounced the vote there as “a sham and a charade.”

The INEC election commission said first results from 120,000 polling stations nationwide should be available on Sunday evening but later pushed this back by 24 hours.

“So far, we have seen no evidence of systemic manipulation of the process,” US Secretary of State John Kerry and British Foreign Secretary Philip Hammond said in a joint statement.

“But there are disturbing indications that the collation process — where the votes are finally counted — may be subject to deliberate political interference,” they added.

The US National Democratic Institute (NDI), which promotes democracy and open government, praised the election despite the hiccups.

“Nigerian voters conducted themselves in a peaceful and orderly manner on election day,” it said. NDI official Christopher Fomunyoh said the group saw no evidence of the military interfering in the poll, as many had feared.

Turnout among the 56.7 million registered voters appears to have been high.

All eyes are now on the collation process, in which historically figures have either been fiddled or sometimes completely made up.

Early results from some of Nigeria’s 36 states had come in by midday, but not enough to indicate any clear front-runner.

In the northern battleground state of Kano, final results gave Buhari 89 percent of the vote. In southern Rivers, where the result is fiercely contested, results showed a Jonathan win by 95 percent.