diff --git a/src/core/diags/factory_diags.cpp b/src/core/diags/factory_diags.cpp
index cb5dd774c..f280d5bca 100644
--- a/src/core/diags/factory_diags.cpp
+++ b/src/core/diags/factory_diags.cpp
@@ -198,9 +198,9 @@ Diags::Diags(Instance &aInstance)
     , mChannel(20)
     , mTxPower(0)
     , mTxLen(0)
+    , mCurTxCmd(kTxCmdNone)
     , mIsTxPacketSet(false)
     , mIsAsyncSend(false)
-    , mRepeatActive(false)
     , mDiagSendOn(false)
     , mOutputCallback(nullptr)
     , mOutputContext(nullptr)
@@ -387,7 +387,7 @@ Error Diags::ProcessRepeat(uint8_t aArgsLength, char *aArgs[])
     if (StringMatch(aArgs[0], "stop"))
     {
         otPlatAlarmMilliStop(&GetInstance());
-        mRepeatActive = false;
+        mCurTxCmd = kTxCmdNone;
     }
     else
     {
@@ -395,6 +395,7 @@ Error Diags::ProcessRepeat(uint8_t aArgsLength, char *aArgs[])
         uint8_t  txLength;
 
         VerifyOrExit(aArgsLength >= 1, error = kErrorInvalidArgs);
+        VerifyOrExit(mCurTxCmd == kTxCmdNone, error = kErrorInvalidState);
 
         SuccessOrExit(error = Utils::CmdLineParser::ParseAsUint32(aArgs[0], txPeriod));
         mTxPeriod = txPeriod;
@@ -415,11 +416,10 @@ Error Diags::ProcessRepeat(uint8_t aArgsLength, char *aArgs[])
 
         VerifyOrExit((txLength >= OT_RADIO_FRAME_MIN_SIZE) && (txLength <= OT_RADIO_FRAME_MAX_SIZE),
                      error = kErrorInvalidArgs);
-        mTxLen = txLength;
 
-        mRepeatActive = true;
-        uint32_t now  = otPlatAlarmMilliGetNow();
-        otPlatAlarmMilliStartAt(&GetInstance(), now, mTxPeriod);
+        mTxLen    = txLength;
+        mCurTxCmd = kTxCmdRepeat;
+        otPlatAlarmMilliStartAt(&GetInstance(), otPlatAlarmMilliGetNow(), mTxPeriod);
     }
 
 exit:
@@ -433,6 +433,7 @@ Error Diags::ProcessSend(uint8_t aArgsLength, char *aArgs[])
     uint8_t  txLength;
 
     VerifyOrExit(aArgsLength >= 1, error = kErrorInvalidArgs);
+    VerifyOrExit(mCurTxCmd == kTxCmdNone, error = kErrorInvalidState);
 
     if (StringMatch(aArgs[0], "async"))
     {
@@ -468,6 +469,7 @@ Error Diags::ProcessSend(uint8_t aArgsLength, char *aArgs[])
     mTxLen = txLength;
 
     SuccessOrExit(error = TransmitPacket());
+    mCurTxCmd = kTxCmdSend;
 
     if (!mIsAsyncSend)
     {
@@ -574,12 +576,14 @@ Error Diags::TransmitPacket(void)
         }
     }
 
-    mDiagSendOn = true;
-    error       = Get<Radio>().Transmit(*static_cast<Mac::TxFrame *>(mTxPacket));
-
-    if (error == kErrorInvalidState)
+    error = Get<Radio>().Transmit(*static_cast<Mac::TxFrame *>(mTxPacket));
+    if (error == kErrorNone)
     {
-        mStats.mSentErrorInvalidStatePackets++;
+        mDiagSendOn = true;
+    }
+    else
+    {
+        UpdateTxStats(error);
     }
 
     return error;
@@ -777,7 +781,7 @@ extern "C" void otPlatDiagAlarmFired(otInstance *aInstance) { AsCoreType(aInstan
 
 void Diags::AlarmFired(void)
 {
-    if (mRepeatActive)
+    if (mCurTxCmd == kTxCmdRepeat)
     {
         uint32_t now = otPlatAlarmMilliGetNow();
 
@@ -872,26 +876,8 @@ void Diags::TransmitDone(Error aError)
         IgnoreError(Get<Radio>().Sleep());
     }
 
-    switch (aError)
-    {
-    case kErrorNone:
-        mStats.mSentSuccessPackets++;
-        break;
-
-    case kErrorChannelAccessFailure:
-        mStats.mSentErrorCcaPackets++;
-        break;
-
-    case kErrorAbort:
-        mStats.mSentErrorAbortPackets++;
-        break;
-
-    default:
-        mStats.mSentErrorOthersPackets++;
-        break;
-    }
-
-    VerifyOrExit(!mRepeatActive && (mTxPackets > 0));
+    UpdateTxStats(aError);
+    VerifyOrExit((mCurTxCmd == kTxCmdSend) && (mTxPackets > 0));
 
     if (mTxPackets > 1)
     {
@@ -901,6 +887,7 @@ void Diags::TransmitDone(Error aError)
     else
     {
         mTxPackets = 0;
+        mCurTxCmd  = kTxCmdNone;
 
         if (!mIsAsyncSend)
         {
@@ -926,6 +913,32 @@ exit:
     return ret;
 }
 
+void Diags::UpdateTxStats(Error aError)
+{
+    switch (aError)
+    {
+    case kErrorNone:
+        mStats.mSentSuccessPackets++;
+        break;
+
+    case kErrorChannelAccessFailure:
+        mStats.mSentErrorCcaPackets++;
+        break;
+
+    case kErrorAbort:
+        mStats.mSentErrorAbortPackets++;
+        break;
+
+    case kErrorInvalidState:
+        mStats.mSentErrorInvalidStatePackets++;
+        break;
+
+    default:
+        mStats.mSentErrorOthersPackets++;
+        break;
+    }
+}
+
 #endif // OPENTHREAD_RADIO
 
 Error Diags::ProcessContinuousWave(uint8_t aArgsLength, char *aArgs[])
diff --git a/src/core/diags/factory_diags.hpp b/src/core/diags/factory_diags.hpp
index 3ff02f61b..53392f28d 100644
--- a/src/core/diags/factory_diags.hpp
+++ b/src/core/diags/factory_diags.hpp
@@ -240,12 +240,20 @@ private:
     void Output(const char *aFormat, ...);
     void ResetTxPacket(void);
     void OutputStats(void);
+    void UpdateTxStats(Error aError);
 
     static bool IsChannelValid(uint8_t aChannel);
 
     static const struct Command sCommands[];
 
 #if OPENTHREAD_FTD || OPENTHREAD_MTD || (OPENTHREAD_RADIO && OPENTHREAD_RADIO_CLI)
+    enum TxCmd : uint8_t
+    {
+        kTxCmdNone,
+        kTxCmdRepeat,
+        kTxCmdSend,
+    };
+
     Stats mStats;
 
     otRadioFrame *mTxPacket;
@@ -254,10 +262,10 @@ private:
     uint8_t       mChannel;
     int8_t        mTxPower;
     uint8_t       mTxLen;
+    TxCmd         mCurTxCmd;
     bool          mIsHeaderUpdated : 1;
     bool          mIsTxPacketSet : 1;
     bool          mIsAsyncSend : 1;
-    bool          mRepeatActive : 1;
     bool          mDiagSendOn : 1;
     bool          mIsSleepOn : 1;
 #endif
diff --git a/tests/scripts/expect/cli-diags.exp b/tests/scripts/expect/cli-diags.exp
index ac30c6089..5f351863c 100755
--- a/tests/scripts/expect/cli-diags.exp
+++ b/tests/scripts/expect/cli-diags.exp
@@ -158,6 +158,18 @@ expect_line "Done"
 send "diag radio receive\n"
 expect_line "Done"
 
+send "diag repeat 100 100\n"
+expect "Done"
+
+send "diag send 1 10\n"
+expect "Error 13: InvalidState"
+
+send "diag repeat stop\n"
+expect "Done"
+
+send "diag send 1 10\n"
+expect "Done"
+
 send_user "shortest frame test\n"
 send "diag frame 112233\n"
 expect "Done"