U.S. advertising companies Omnicom Group Inc and Interpublic Group of Cos reported better-than-expected revenue, mainly due to higher ad spending in their home market.

Omnicom, the largest U.S. advertising company and owner of agencies such as BBDO Worldwide and Goodby, Silverstein & Partners, said U.S. revenue rose 4 percent in the first quarter.

Closest rival Interpublic, home to agencies including McCann Erickson and Draftfcb, said its U.S. revenue increased 5 percent.

"We saw solid contributions from across our agency portfolio, with strength in the U.S., as well as significant growth in Latin America and Asia," Interpublic Chief Executive Michael Roth said in a statement on Tuesday.

Omnicom, which is in the middle of a $35.1 billion merger with France's Publicis Groupe SA, said total revenue rose 3 percent to $3.50 billion.

Analysts on average had expected revenue of $3.48 billion, according to Thomson Reuters I/B/E/S.

Interpublic's revenue rose 6.1 percent to $1.64 billion, beating the average analyst estimate of $1.60 billion.

International revenue increased 7.7 percent after three quarters of decline.

Omnicom's adjusted profit also came in above expectations, while Interpublic reported a smaller-than-expected loss in the quarter ended March 31.

Omnicom's net income available for common shareholders rose slightly to $201.4 million, or 77 cents per share.

Excluding merger expenses, the company earned 80 cents per share, above the average analyst estimate of 79 cents.

Interpublic reported a net loss attributable to common shareholders of $20.9 million, or 5 cents per share.

Analysts had expected a loss of 8 cents per share.

Omnicom said organic growth increased revenue by 4.3 percent.

Interpublic reported a 6.6 percent rise in organic revenue and said it remained "well-positioned to meet or exceed" its 2014 target of 3 to 4 percent organic growth and operating margin of 10.3 percent or better.