(Bloomberg) -- The Republic of Congo’s government denied speculation on social media that there had been a coup in the central African nation.

“Fanciful information suggests there may be serious events underway in Brazzaville,” government spokesman Thierry Moungalla said in a statement posted on Twitter, referring to the Congolese capital. “The government denies this fake news.”

Speculation of a military takeover surfaced on social media on Sunday, as President Denis Sassou Nguesso traveled to New York to attend the United Nations General Assembly this week. Investor concern about political discontent in Congo has led to a selloff of the nation’s dollar bonds in the wake of a military takeover in neighboring Gabon last month, with the yield on Congolese debt due in 2029 rising almost 600 basis points this month to 13.30% — the highest level this year.

The rate on the bonds rose 16 basis points to 13.46% by 10:19 a.m. in London on Monday.

Read More: Gabon Coup Triggers Bond Selloff Sparking Contagion Fears

Sassou Nguesso, 79, has ruled Congo with an iron fist for almost four decades. He led the country from 1979 to 1992 and then returned to power at the end of a civil war in 1997, winning a fourth five-year term as president in elections two years ago.

Investors have also been jittery about potential instability in neighboring Cameroon, where President Paul Biya has been in power since 1982. Biya last month appointed new military officials in the wake of the Aug. 30 coup in Gabon, and last week banned a local newspaper over a headline about a survey on military coups.

The yield on Cameroon’s euro-denominated debt due in 2032 has risen almost 100 basis points since the Gabon putsch to 12.34% on Monday.

Read More: Another Coup in Francophone Africa Shatters Macron’s Strategy

--With assistance from Rene Vollgraaff.

(Updates with bond movements and Gabon details from fourth paragraph)

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